Liquid-crystal medium

ABSTRACT

The present invention relates to a liquid crystal (LC) medium comprising polymerisable compounds, to a process for its preparation, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, and to LC displays comprising it.

The present invention relates to a liquid crystal (LC) medium comprisingpolymerisable compounds, to a process for its preparation, to its usefor optical, electro-optical and electronic purposes, in particular inflexible LC displays, and to LC displays comprising it.

BACKGROUND OF THE INVENTION

Recently liquid crystal (LC) mixtures have been developed for therealization of flexible substrate based LC displays. These LC mixturescontain reactive polymer precursors that allow the formation of polymerwalls in the display, which help to maintain the gap distance of the LClayer. This technology thus enables manufacturing of free form androbust displays by using LC materials.

Free form LC displays can either have a permanent shape other than arigid flat panel displays, for example a curved shape, or can even beflexible. The simplest form of the first type are curved TVs that havebeen developed in the recent past and offer the viewer an enhancedviewing experience. Thereby it is possible to provide displays that arenot only shaped in one, but two dimensions, and could be used forexample as car dashboards or advertising screens.

Flexible displays, another type of free form displays, have also beendeveloped, and have been proposed for example for use in mobile phonesor smart watches utilizing the advantages of flexibility. Furtherpotential applications are foldable or rollable mobile phones, as wellas extra-large screens for presentations or home entertainment, whichrequire due to their size to be rollable or foldable for beingtransported or stowed. Advantageously such devices are based on plasticsubstrates, instead of rigid glass substrates as used in conventional,unflexible LC displays.

Another display concept, ‘unbreakable’ displays, are also based onplastic substrates and refers to a display design featuring particularrobustness, durability, and resistance against mechanical impact. Oneproblem that should be solved is that mobile devices have an elevatedrisk of being dropped accidentally or becoming otherwise damaged duringtheir normal use. In view of the high value of these devices, a solutionto this problem would be highly desirable.

There is thus a great demand for free form or unbreakable LC displays.

One of the main technical challenges of LC displays with flexiblesubstrates is that the LC layer thickness is critical for proper deviceoperation. A proper combination of defined LC layer thickness and LCmaterial properties ensures that the pixels can be switched between ablack state and light transmitting state. In case of a varying layerthickness, unwanted interference with the gap distance between thesubstrates can result in visible optical defects. It should therefore beensured that the LC layer thickness is not influenced by the bending orthe lack of rigidity of flexible plastic substrates.

In conventional LC displays with rigid glass substrates, usually spacerparticles are added to the LC layer in order to define and maintain aconstant layer thickness. A possible solution for free form displays isto adapt this concept by incorporating supporting structures, like forexample polymer walls, that can both resist compression and bind the twosubstrates together. A suitable manufacturing process is to prefabricatethe polymer wall structures, spread the LC mixture on the substrate, andsubsequently close the panel with the top substrate. Potential problemswith this approach are for example that spreading of the LC mixture isobstructed by the support structures, and that bonding to the topsubstrate might not be sufficient.

An alternative solution is to create the polymer wall structures bymeans of a photolithographic process after the display has beenassembled. This is schematically illustrated in FIG. 1 showing a polymerwall formation process. FIG. 1 (a) shows an LC mixture consisting of LChost molecules (rods), polymerisable monomer (dots), and photo-initiator(not shown). As shown in FIG. 1 (b) the LC mixture is filled into thedisplay, or the LC mixture is spread on a first substrate and a secondsubstrate applied on top, and UV radiation (indicated by the arrows) isapplied through a photomask. Polymerization induced phase separationtakes place, as a result of which polymer walls are formed in irradiatedregions according to the mask pattern as shown in FIG. 1 (c), while theLC phase of the LC host molecules (rods) in the pixel area is restored.

The principle of creating polymer walls by this method for LC displayapplications is a known technique that has been described in theliterature and has been suggested for use in a variety of display modes.

For example, U.S. Pat. No. 6,130,738 and EP2818534 A1 disclose an LCdisplay that comprises polymer walls formed from one or twopolymerisable monomers that are contained in the LC host mixture.

However, the currently used LC mixtures and monomers for use in flexibleLC displays with polymer wall formation do still have several drawbacksand leave room for further improvement.

For example, it was observed that the polymerisable compounds and LCmedia used in prior art do often show insufficient phase separationbetween the polymer walls and the LC molecules of the LC host mixture.This leads on the one hand to the undesired inclusion of LC molecules inthe polymer walls, and on the other hand to increased amounts of polymermolecules dissolved or dispersed in the LC host mixture, both of whichcan negatively influence the display performance.

Thus, LC molecules trapped in the polymer wall can lead to reducedtransparency and contrast of the display, a deterioration of theelectrooptical response due to formation of domains with differentswitching speed, and decreased adhesion of the polymer walls to thesubstrates. On the other hand, undesired amounts of polymer molecules inthe LC host mixture can negatively affect the LC mixture properties.

Moreover, it was observed that the thickness of the polymer walls isoften not constant but varying, which can lead to non-uniform pixelsize. Besides the polymer walls do often still not show sufficientstability against mechanical pressure on the one hand and sufficientelasticity on the other hand. Also, the polymer walls are often toothick, which reduces transparency and contrast of the display.

It is therefore desirable to have available improved LC mixtures andmonomers for use in flexible LC displays which can overcome thedrawbacks of materials used in prior art as described above.

The present invention is based on the object of providing novel suitablematerials, in particular LC host mixtures comprising polymerisablemonomers, for use in flexible LC displays with polymer walls, which donot have the disadvantages indicated above or do so only to a reducedextent.

In particular, the invention is based on the object of providing LCmedia comprising polymerisable monomers, which enable the formation ofpolymer walls in a time- and cost-effective manner, and which aresuitable for mass production. The formed polymer walls should show clearphase separation from the LC host mixture, without or with a reducedamount of defects or LC molecules trapped in the polymer wall, andwithout or with a reduced amount of polymer molecules dissolved in theLC host mixture. Also, the polymer walls should show constant thickness,high elasticity, high stability against mechanical pressure, and goodadhesion to the substrates.

Another object of the invention is to provide improved LC host mixturesfor flexible displays which should show high specific resistance values,high VHR values, high reliability, low threshold voltages, shortresponse times, high birefringence, show good UV absorption especiallyat longer wavelengths, allow quick and complete polymerisation of themonomers contained therein, and reduce or prevent the occurrence ofimage sticking in the display.

Another object of the invention is to provide LC displays with polymerwalls that show high transparency in the addressed state, good contrast,high switching speed and a large operating temperature range.

Another object of the present invention is to provide an improvedtechnical solution for enabling LCD technology for free form andunbreakable plastic substrate based LC displays.

The above objects have been achieved in accordance with the presentinvention by materials and processes as described and claimedhereinafter.

Thus, it has surprisingly been found that at least some of theabove-mentioned objects can be achieved by using an LC medium whichcomprises an LC host mixture and one or more polymerisable monomers asdisclosed and claimed hereinafter, which contains a polymerisablecompound having a polymerisable group and a cycloalkyl group to the LCmedium. It was observed that, by using such an LC medium, it is possibleto achieve polymer walls with a more constant thickness and better phaseseparation between the polymer walls and the LC host mixture.

It has also been surprisingly found that the polymerisable compoundscontained in the LC medium can also be used to form spacers to maintaina constant cell gap between the substrates of the LC display. This cansupport or even replace the spacer materials that are normally used inprior art.

SUMMARY OF THE INVENTION

The invention relates to a liquid crystal (LC) medium comprising apolymerisable component A) which comprises, and preferably consists of,one or more polymerisable compounds, and a liquid-crystalline componentB), hereinafter also referred to as “LC host mixture”, which comprises,and preferably consists of, one or more mesogenic or liquid-crystallinecompounds, wherein the polymerisable component A) comprises

one or more first polymerisable compounds comprising a monocyclichydrocarbon group having from 8 to 24 ring atoms and attached thereto(exactly) one polymerisable group,

optionally one or more second polymerisable compounds comprising astraight-chain or branched hydrocarbon group having from 1 to 30 Catoms, or a monocyclic hydrocarbon group having from 3 to 7 ring atoms,or a bi- or polycyclic hydrocarbon group having from 4 to 30 ring atoms,and attached thereto (exactly) one polymerisable group,

optionally one or more third polymerisable compounds comprising astraight-chain, branched or cyclic hydrocarbon group having from 1 to 30C atoms, and attached thereto two or more polymerisable groups, and

optionally one or more fourth polymerisable compounds comprising a ringsystem containing one or more aromatic or heteroaromatic rings orcondensed aromatic or heteroaromatic rings, and attached thereto twopolymerisable groups that are preferably different from each other.

The liquid-crystalline component B) of an LC medium according to thepresent invention is hereinafter also referred to as “LC host mixture”,and preferably contains LC compounds that are selected only fromlow-molecular-weight compounds which are unpolymerisable, and optionallycontains further additives like photoinitiators, stabilisers or chiraldopants.

The invention furthermore relates to an LC medium or LC display asdescribed above and below, wherein the polymerisable compounds, or thecompounds of component A), are polymerised.

The invention furthermore relates to a process for preparing an LCmedium as described above and below, comprising the steps of mixing anLC host mixture or LC component B) as described above and below, withone or more polymerisable compounds as described above and below, andoptionally with further LC compounds and/or additives.

The invention further relates to the use of LC medium in LC displays,preferably in flexible LC displays.

The invention furthermore relates to an LC display comprising an LCmedium as described above and below.

The invention furthermore relates to an LC display comprising polymerwalls obtainable by polymerisation of one or more polymerisablecompounds or a polymerisable component A) as described above and below,or comprising an LC medium as described above and below.

The invention furthermore relates to an LC display comprising spacersobtainable by polymerisation of one or more polymerisable compounds or apolymerisable component A) as described above and below, or comprisingan LC medium as described above and below.

The LC display according to the present invention is preferably aflexible LC display, and preferably a TN, OCB, IPS, FFS, posi-VA, VA orUB-FFS display.

The invention furthermore relates to an LC display comprising twosubstrates, at least one which is transparent to light, an electrodeprovided on each substrate or two electrodes provided on only one of thesubstrates, and located between the substrates a layer of an LC mediumas described above and below, wherein the polymerisable compounds arepolymerised between the substrates of the display.

The invention furthermore relates to a process for manufacturing an LCdisplay as described above and below, comprising the steps of filling orotherwise providing an LC medium as described above and below betweenthe substrates of the display, and polymerising the polymerisablecompounds.

The displays according to the invention have two electrodes, preferablyin the form of transparent layers, which are applied to one or both ofthe substrates. In some displays, for example in TN, OCB or VA displays,one electrode is applied to each of the two substrates. In otherdisplays, for example in IPS, FFS or UB-FFS displays, both electrodesare applied to only one of the two substrates.

The polymerisable compounds of the polymerisable component arepreferably polymerised by photopolymerisation, very preferably by UVphotopolymerisation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates the polymer wall formation process indisplays according to prior art and according to the present invention.

FIG. 2-9 show polarization microscope images of test cells containingpolymerisable mixtures 1-8 according to Use Examples 1-8, respectively,after polymerization.

FIG. 10-18 show polarization microscope images of test cells containingpolymerisable mixtures 9-17 according to Use Examples 9-17,respectively, after polymerization (a), after mechanical stress test (b)and after thermal stress test (c).

DETAILED DESCRIPTION OF THE INVENTION

Above and below, the term “free form display” will be understood to meana display that has either a permanent shape other than a plane-parallelshape, like for example a curved shape, or a flexible display. The term“flexible display” will be understood to mean a display which isbendable without breaking, like for example a display having flexibleplastic substrates instead of rigid glass substrates and not comprisingany other rigid layers. The term “curved display” will be understood tomean a display which has top and bottom substrates that are notplane-parallel but curved.

Above and below, the term “flat display with reduced touch Murasensitivity” will be understood to mean a display wherein irregularluminosity variation defects, which are caused by touching the frontscreen of a display, are reduced.

Above and below, the term “bi- or polycyclic group” will be understoodto mean a group that consists of two or more fused rings, i.e. ringsthat share at last one common atom (in contrast to rings that areconnected via covalent bonds between atoms belonging to differentrings), wherein fusion of the rings occurs

a) across a sequence of atoms (bridgehead), like for example inbicyclo[2.2.1]heptane (norbornane) or tricyclo[3.3.3.1]decane(adamantane), hereinafter also referred to as “bridged bi- or polycyclicgroups”,

b) across a bond between two atoms, like for example inbicyclo[4.4.0]decane (decalin), hereinafter also referred to as “fusedbi- or polycyclic groups”

c) at a single atom (spiro atom), like for example in spiro[4.5]decane,hereinafter also referred to as “spirocyclic groups”.

Unless indicated otherwise, the abbreviation “RM” is used above andbelow when referring to a reactive mesogen.

Above and below, polymerisable compounds or RMs with one polymerisablereactive group are also referred to as “monoreactive”, polymerisablecompounds or RMs with two polymerisable reactive groups are alsoreferred to as “direactive”, and polymerisable compounds or RMs withthree polymerisable reactive groups are also referred to as“trireactive”.

Unless indicated otherwise, the expression “LC mixture” is used whenreferring to the LC host mixture (i.e. without the RMs or polymerizablecompounds), while the expression “LC medium” is used when referring tothe LC host mixture plus the RM(s) or polymerizable compounds.

Unless stated otherwise, the polymerisable compounds and RMs arepreferably selected from achiral compounds.

As used herein, the terms “active layer” and “switchable layer” mean alayer in an electrooptical display, for example an LC display, thatcomprises one or more molecules having structural and opticalanisotropy, like for example LC molecules, which change theirorientation upon an external stimulus like an electric or magneticfield, resulting in a change of the transmission of the layer forpolarized or unpolarized light.

As used herein, the terms “reactive mesogen” and “RM” will be understoodto mean a compound containing a mesogenic or liquid crystallineskeleton, and one or more functional groups attached thereto which aresuitable for polymerisation and are also referred to as “polymerisablegroup” or “P”.

Unless stated otherwise, the term “polymerisable compound” as usedherein will be understood to mean a polymerisable monomeric compound.

As used herein, the term “low-molecular-weight compound” will beunderstood to mean to a compound that is monomeric and/or is notprepared by a polymerisation reaction, as opposed to a “polymericcompound” or a “polymer”.

As used herein, the term “unpolymerisable compound” will be understoodto mean a compound that does not contain a functional group that issuitable for polymerisation under the conditions usually applied for thepolymerisation of the RMs or polymerizable compounds.

The term “mesogenic group” as used herein is known to the person skilledin the art and described in the literature, and means a group which, dueto the anisotropy of its attracting and repelling interactions,essentially contributes to causing a liquid-crystal (LC) phase inlow-molecular-weight or polymeric substances. Compounds containingmesogenic groups (mesogenic compounds) do not necessarily have to havean LC phase themselves. It is also possible for mesogenic compounds toexhibit LC phase behaviour only after mixing with other compounds and/orafter polymerisation. Typical mesogenic groups are, for example, rigidrod- or disc-shaped units. An overview of the terms and definitions usedin connection with mesogenic or LC compounds is given in Pure Appl.Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew.Chem. 2004, 116, 6340-6368.

The term “spacer group”, hereinafter also referred to as “Sp”, as usedherein is known to the person skilled in the art and is described in theliterature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C.Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. Asused herein, the terms “spacer group” or “spacer” mean a flexible group,for example an alkylene group, which connects the mesogenic group andthe polymerisable group(s) in a polymerisable mesogenic compound.

Above and below,

denote a trans-1,4-cyclohexylene ring, and

denote a 1,4-phenylene ring.

Above and below “organic group” denotes a carbon or hydrocarbon group.

“Carbon group” denotes a mono- or polyvalent organic group containing atleast one carbon atom, where this either contains no further atoms (suchas, for example, —C≡C—) or optionally contains one or more furtheratoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge (forexample carbonyl, etc.). The term “hydrocarbon group” denotes a carbongroup which additionally contains one or more H atoms and optionally oneor more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Teor Ge.

“Halogen” denotes F, Cl, Br or I.

—CO—, —C(═O)— and —C(O)— denote a carbonyl group, i.e.

A carbon or hydrocarbon group can be a saturated or unsaturated group.Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. Acarbon or hydrocarbon radical having more than 3 C atoms can bestraight-chain, branched and/or cyclic and may also contain spiro linksor condensed rings.

The terms “alkyl”, “aryl”, “heteroaryl”, etc., also encompass polyvalentgroups, for example alkylene, arylene, heteroarylene, etc.

The term “aryl” denotes an aromatic carbon group or a group derivedtherefrom. The term “heteroaryl” denotes “aryl” as defined above,containing one or more heteroatoms, preferably selected from N, O, S,Se, Te, Si and Ge.

Preferred carbon and hydrocarbon groups are optionally substituted,straight-chain, branched or cyclic, alkyl, alkenyl, alkynyl, alkoxy,alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxyhaving 1 to 40, preferably 1 to 20, very preferably 1 to 12, C atoms,optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to25, C atoms, or optionally substituted alkylaryl, arylalkyl,alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl,arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to25, C atoms, wherein one or more C atoms may also be replaced by heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.

Further preferred carbon and hydrocarbon groups are C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, C₃-C₂₀ allyl, C₄-C₂₀ alkylidenyl, C₄-C₂₀polyenyl, C₆-C₂₀ cycloalkyl, C₄-C₁₅ cycloalkenyl, C₆-C₃₀ aryl, C₆-C₃₀alkylaryl, C₆-C₃₀ arylalkyl, C₆-C₃₀ alkylaryloxy, C₆-C₃₀ arylalkyloxy,C₂-C₃₀ heteroaryl, C₂-C₃₀ heteroaryloxy.

Particular preference is given to C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂alkynyl, C₆-C₂₅ aryl and C₂-C₂₅ heteroaryl.

Further preferred carbon and hydrocarbon groups are straight-chain,branched or cyclic alkyl having 1 to 20, preferably 1 to 12, C atoms,which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I orCN and in which one or more non-adjacent CH₂ groups may each bereplaced, independently of one another, by —C(R^(x))═C(R^(x))—, —C≡C—,—N(R^(x))—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way thatO and/or S atoms are not linked directly to one another, and

R^(x) denotes H, F, Cl, CN, a straight-chain, branched or cyclic alkylchain having 1 to 25 C atoms, in which, in addition, one or morenon-adjacent C atoms may be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—,—O—CO—O— and in which one or more H atoms may be replaced by F or Cl, ordenotes an optionally substituted aryl or aryloxy group with 6 to 30 Catoms, or an optionally substituted heteroaryl or heteroaryloxy groupwith 2 to 30 C atoms.

Preferred alkyl groups are, for example, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl,s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl,cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl,n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl,2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.

Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl,pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl,octenyl, cyclooctenyl, etc.

Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl,pentynyl, hexynyl, octynyl, etc.

Preferred alkoxy groups are, for example, methoxy, ethoxy,2-methoxy-ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy,t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy,n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, etc.

Preferred amino groups are, for example, dimethylamino, methylamino,methylphenylamino, phenylamino, etc.

Aryl and heteroaryl groups can be monocyclic or polycyclic, i.e. theycan contain one ring (such as, for example, phenyl) or two or morerings, which may also be fused (such as, for example, naphthyl) orcovalently bonded (such as, for example, biphenyl), or contain acombination of fused and linked rings. Heteroaryl groups contain one ormore heteroatoms, preferably selected from O, N, S and Se.

Particular preference is given to mono-, bi- or tricyclic aryl groupshaving 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl groupshaving 5 to 25 ring atoms, which optionally contain fused rings and areoptionally substituted. Preference is furthermore given to 5-, 6- or7-membered aryl and heteroaryl groups, in which, in addition, one ormore CH groups may be replaced by N, S or O in such a way that O atomsand/or S atoms are not linked directly to one another.

Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl,[1,1′:3′,1″]terphenyl-2′-yl, naphthyl, anthracene, binaphthyl,phenanthrene, 9,10-dihydro-phenanthrene, pyrene, dihydropyrene,chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene,indenofluorene, spirobifluorene, etc.

Preferred heteroaryl groups are, for example, 5-membered rings, such aspyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole,furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole,1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole,1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole,1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings, such aspyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine,1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine,1,2,3,5-tetrazine, or condensed groups, such as indole, isoindole,indolizine, indazole, benzimidazole, benzotriazole, purine,naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole,quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole,phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran,dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline,benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine,phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine,quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline,phenanthridine, phenanthroline, thieno[2,3b]thiophene,thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene,dibenzothiophene, benzothiadiazothiophene, or combinations of thesegroups.

The aryl and heteroaryl groups mentioned above and below may also besubstituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl orfurther aryl or heteroaryl groups.

The (non-aromatic) alicyclic and heterocyclic groups encompass bothsaturated rings, i.e. those containing exclusively single bonds, andalso partially unsaturated rings, i.e. those which may also containmultiple bonds. Heterocyclic rings contain one or more heteroatoms,preferably selected from Si, O, N, S and Se.

The (non-aromatic) alicyclic and heterocyclic groups can be monocyclic,i.e. contain only one ring (such as, for example, cyclohexane), orpolycyclic, i.e. contain a plurality of rings (such as, for example,decahydronaphthalene or bicyclooctane). Particular preference is givento saturated groups. Preference is furthermore given to mono-, bi- ortricyclic groups having 5 to 25 ring atoms, which optionally containfused rings and are optionally substituted. Preference is furthermoregiven to 5-, 6-, 7- or 8-membered carbocyclic groups, in which, inaddition, one or more C atoms may be replaced by Si and/or one or moreCH groups may be replaced by N and/or one or more non-adjacent CH₂groups may be replaced by —O— and/or —S—.

Preferred alicyclic and heterocyclic groups are, for example, 5-memberedgroups, such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran,pyrrolidine, 6-membered groups, such as cyclohexane, silinane,cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane,1,3-dithiane, piperidine, 7-membered groups, such as cycloheptane, andfused groups, such as tetrahydronaphthalene, decahydronaphthalene,indane, bicyclo[1.1.1]-pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl,spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindane-2,5-diyl.

Preferred substituents are, for example, solubility-promoting groups,such as alkyl or alkoxy, electron-withdrawing groups, such as fluorine,nitro or nitrile, or substituents for increasing the glass transitiontemperature (Tg) in the polymer, in particular bulky groups, such as,for example, t-butyl or optionally substituted aryl groups.

Preferred substituents, hereinafter also referred to as L^(S), are, forexample, F, Cl, Br, I, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN,—C(═O)N(R^(x))₂, —C(═O)Y¹, —C(═O)R^(x), —N(R^(x))₂, straight-chain orbranched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxyor alkoxycarbonyloxy each having 1 to 25 C atoms, in which one or more Hatoms may optionally be replaced by F or Cl, optionally substitutedsilyl having 1 to 20 Si atoms, or optionally substituted aryl having 6to 25, preferably 6 to 15, C atoms,

wherein R^(x) denotes H, F, Cl, CN, or straight chain, branched orcyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacentCH₂-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—,—O—CO—O— in such a manner that O- and/or S-atoms are not directlyconnected with each other, and wherein one or more H atoms are eachoptionally replaced by F, Cl, P- or P-Sp-, and

Y¹ denotes halogen.

“Substituted silyl or aryl” preferably means substituted by halogen,—CN, R⁰, —OR⁰, —CO—R⁰, —CO—O—R⁰, —O—CO—R⁰ or —O—CO—O—R⁰, wherein R⁰denotes H or alkyl with 1 to 20 C atoms.

Particularly preferred substituents L are, for example, F, Cl, CN, NO₂,CH₃, C₂H₅, OCH₃, OC₂H₅, COCH₃, COC₂H₅, COOCH₃, COOC₂H₅, CF₃, OCF₃,OCHF₂, OC₂F₅, furthermore phenyl.

is preferably

in which L has one of the meanings indicated above.

The polymerisable group P or P^(1,2) is a group which is suitable for apolymerisation reaction, such as, for example, free-radical or ionicchain polymerisation, polyaddition or polycondensation, or for apolymer-analogous reaction, for example addition or condensation onto amain polymer chain. Particular preference is given to groups for chainpolymerisation, in particular those containing a C═C double bond or—C≡C— triple bond, and groups which are suitable for polymerisation withring opening, such as, for example, oxetane or epoxide groups.

Preferred groups P and P^(1,2) are selected from the group consisting ofCH₂═CW¹—CO—O—, CH₂═CW¹—CO—,

CH₂═CW²—(O)_(k3)—, CW¹═CH—CO—(O)_(k3)—, CW¹═CH—CO—NH—, CH₂═CW¹—CO—NH—,CH₃—CH═CH—O—, (CH₂═CH)₂CH—OCO—, (CH₂═CH—CH₂)₂CH—OCO—, (CH₂═CH)₂CH—O—,(CH₂═CH—CH₂)₂N—, (CH₂═CH—CH₂)₂N—CO—, HO—CW²W³—, HS—CW²W³—, HW²N—,HO—CW²W³—NH—, CH₂═CW¹—CO—NH—, CH₂═CH—(COO)_(k1)-Phe-(O)_(k2)—,CH₂═CH—(CO)_(k1)-Phe-(O)_(k2)—, Phe-CH═CH—, HOOC—, OCN— and W⁴W⁵W⁶Si—,in which W¹ denotes H, F, Cl, CN, CF₃, phenyl or alkyl having 1 to 5 Catoms, in particular H, F, Cl, CH₃ or C₂H₅, W² and W³ each,independently of one another, denote H or alkyl having 1 to 5 C atoms,in particular H, methyl, ethyl or n-propyl, W⁴, W⁵ and W⁶ each,independently of one another, denote Cl, oxaalkyl or oxacarbonylalkylhaving 1 to 5 C atoms, W⁷ and W⁸ each, independently of one another,denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene,which is optionally substituted by one or more radicals L as definedabove which are other than P-Sp-, k₁, k₂ and k₃ each, independently ofone another, denote 0 or 1, k₃ preferably denotes 1, and k₄ denotes aninteger from 1 to 10.

Very preferred groups P and P^(1,2) are selected from the groupconsisting of CH₂═CW¹—CO—O—, CH₂═CW¹—CO—,

CH₂═CW²—O—, CH₂═CW²—, CW¹═CH—CO—(O)_(k3)—, CW¹═CH—CO—NH—,CH₂═CW¹—CO—NH—, (CH₂═CH)₂CH—OCO—, (CH₂═CH—CH₂)₂CH—OCO—, (CH₂═CH)₂CH—O—,(CH₂═CH—CH₂)₂N—, (CH₂═CH—CH₂)₂N—CO—, CH₂═CW¹—CO—NH—,CH₂═CH—(COO)_(k1)-Phe-(O)_(k2)—, CH₂═CH—(CO)_(k1)-Phe-(O)_(1,2)-,Phe-CH═CH— and W⁴W⁵W⁶Si—, in which W¹ denotes H, F, Cl, CN, CF₃, phenylor alkyl having 1 to 5 C atoms, in particular H, F, Cl, CH₃ or C₂H₅, W²and W³ each, independently of one another, denote H or alkyl having 1 to5 C atoms, in particular H, methyl, ethyl or n-propyl, W⁴, W⁵ and W⁶each, independently of one another, denote Cl, oxaalkyl oroxacarbonylalkyl having 1 to 5 C atoms, W⁷ and W⁸ each, independently ofone another, denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes1,4-phenylene, k₁, k₂ and k₃ each, independently of one another, denote0 or 1, k₃ preferably denotes 1, and k₄ denotes an integer from 1 to 10.

Very particularly preferred groups P and P^(1,2) are selected from thegroup consisting of CH₂═CW¹—CO—O—, in particular CH₂═CH—CO—O—,CH₂═C(CH₃)—CO—O— and CH₂═CF—CO—O—, furthermore CH₂═CH—O—,(CH₂═CH)₂CH—O—CO—, (CH₂═CH)₂CH—O—,

Further preferred polymerisable groups P and P^(1,2) are selected fromthe group consisting of vinyloxy, acrylate, methacrylate, ethacrylate,fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferablyfrom acrylate and methacrylate.

If Sp or Sp^(1,2) is different from a single bond, it is preferablyselected of the formula Sp″-X″, so that the respective radical P-Sp-conforms to the formula P-Sp″-X″—, wherein

-   Sp″ denotes alkylene having 1 to 20, preferably 1 to 12, C atoms,    which is optionally mono- or polysubstituted by F, Cl, Br, I or CN    and in which, in addition, one or more non-adjacent CH₂ groups may    each be replaced, independently of one another, by —O—, —S—, —NH—,    —N(R⁰)—, —Si(R⁰R⁰⁰)—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—,    —CO—S—, —N(R⁰⁰)—CO—O—, —O—CO—N(R⁰)—, —N(R⁰)—CO—N(R⁰⁰)—, —CH═CH— or    —C≡C— in such a way that O and/or S atoms are not linked directly to    one another,-   X″ denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CO—N(R⁰)—,    —N(R⁰)—CO—, —N(R⁰)—CO—N(R⁰⁰)—, —OCH₂—, —CH₂O—, —SCH₂—, —CH₂S—,    —CF₂O—, —OCF₂—, —CF₂S—, —SCF₂—, —CF₂CH₂—, —CH₂CF₂—, —CF₂CF₂—,    —CH═N—, —N═CH—, —N═N—, —CH═CR⁰—, —CY²═CY³—, —C≡C—, —CH═CH—CO—O—,    —O—CO—CH═CH— or a single bond,-   R⁰ and R⁰⁰ each, independently of one another, denote H or alkyl    having 1 to 20 C atoms, and-   Y² and Y³ each, independently of one another, denote H, F, Cl or CN.-   X″ is preferably —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR⁰—,    —NR⁰—CO—, —NR⁰—CO—NR⁰⁰— or a single bond.

Typical spacer groups Sp, Sp^(1,2) and -Sp″-X″— are, for example,—(CH₂)_(p1)—, —(CH₂CH₂O)_(q1)—CH₂CH₂—, —CH₂CH₂—S—CH₂CH₂—,—CH₂CH₂—NH—CH₂CH₂— or —(SiR⁰R⁰⁰—O)_(p1)—, in which p1 is an integer from1 to 12, q1 is an integer from 1 to 3, and R⁰ and R⁰⁰ have the meaningsindicated above.

Particularly preferred groups Sp, Sp^(1,2) and -Sp″-X″— are—(CH₂)_(p1)—, —(CH₂)_(p1)—O—, —(CH₂)_(p1)—O—CO—, —(CH₂)_(p1)—CO—O—,—(CH₂)_(p1)—O—CO—O—, in which p1 and q1 have the meanings indicatedabove.

Particularly preferred groups Sp″ are, in each case straight-chain,ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene,nonylene, decylene, undecylene, dodecylene, octadecylene,ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene,ethylene-N-methylimino-ethylene, 1-methylalkylene, ethenylene,propenylene and butenylene.

The LC medium according to the present invention contains apolymerisable component A) comprising one or more first polymerisablecompounds with a polymerisable group and a ≥8-membered monocycylichydrocarbon group, one or more second polymerisable compounds comprisinga polymerisable group and a straight-chain, branched or <8-memberedmonocyclic hydrocarbon group, and one or more third polymerisablecompounds comprising two or more polymerisable groups and astraight-chain, branched or monocyclic hydrocarbon group.

The hydrocarbon group contained in the first, second and thirdpolymerisable compounds is preferably a non-aromatic group.

Preferably the monocyclic hydrocarbon group in the first polymerisablecompound is a cycloalkyl group having from 8 to 24 ring atoms,preferably having from 8 to 18 ring atoms, that is optionallysubstituted by one or more groups L as defined in formula I, and whereinone or more CH₂-groups are optionally replaced by —O— and/or —CO— suchthat O-atoms are not directly adjacent to one another.

Preferably component A) of the LC medium comprises one or more firstpolymerisable compounds selected of formula I

P-Sp-G¹  I

wherein

-   P is a polymerisable group,-   Sp is a spacer group or a single bond,-   G¹ is a monocyclic hydrocarbon group having 8 to 24 ring atoms,    preferably 8 to 18 ring atoms, which is optionally substituted by    one or more groups L,-   L is F, Cl, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R^(x))₂,    —C(═O)Y¹, —C(═O)R^(x), —N(R^(x))₂, optionally substituted silyl,    optionally substituted aryl or heteroaryl having 5 to 20 ring atoms,    or straight-chain or branched alkyl having 1 to 25, particularly    preferably 1 to 10, C atoms, in which, in addition, one or more    non-adjacent CH₂ groups may each be replaced, independently of one    another, by —C(R⁰)═C(R⁰⁰)—, —C≡C—, —N(R⁰)—, —O—, —S—, —CO—, —CO—O—,    —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked    directly to one another, and in which, in addition, one or more H    atoms may be replaced by F, Cl, —CN,-   R^(x) is H, F, Cl, CN, or straight chain, branched or cyclic alkyl    having 1 to 25 C atoms, wherein one or more non-adjacent CH₂-groups    are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—    in such a manner that O- and/or S-atoms are not directly connected    with each other, and wherein one or more H atoms are each optionally    replaced by F or Cl,-   R⁰, R⁰⁰ are H or alkyl having 1 to 20 C atoms,-   Y¹ is halogen, preferably F or Cl.

P is preferably acrylate, methacrylate or oxetane, very preferablyacrylate or methacrylate.

Sp is preferably of the formula Sp″-X″, so that the respective radicalP-Sp-conforms to the formula P-Sp″-X″—, wherein Sp″ and X″ are asdefined above.

Sp is very preferably —(CH₂)_(p1)—, —(CH₂)_(p1)—O—, —(CH₂)_(p1)—O—CO—,—(CH₂)_(p1)—CO—O—, —(CH₂)_(p1)—O—CO—O—, in which p1 is an integer from 1to 12.

L is preferably selected from F, Cl, —CN and straight-chain or branchedalkyl having 1 to 25, particularly preferably 1 to 10, C atoms, inwhich, in addition, one or more non-adjacent CH₂ groups may each bereplaced, independently of one another, by —C(R⁰)═C(R⁰⁰)—, —C≡C—,—N(R⁰)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that Oand/or S atoms are not linked directly to one another, and in which, inaddition, one or more H atoms may be replaced by F, Cl, Br, I or CN.

L is very preferably selected from F, —CN, and alkyl or alkoxy with 1 to6 C atoms that is optionally fluorinated, preferably F, Cl, CN, CH₃,OCH₃, OCF₃, OCF₂H or OCFH₂, very preferably F.

G¹ is preferably selected the group consisting of cyclooctyl,cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, cyclotridecyl,cyclotetradecyl, cylcopentadecyl, cyclohexadecyl, cycloheptadecyl andcyclooctadecyl, all of which are optionally substituted by one or moregroups L.

Preferred compounds of formula I are selected from the followingformulae

wherein P and Sp have the meanings given in formula I or one of thepreferred meanings given above and below.

Very preferred compounds of formula I are selected from the followingformulae

Preferably component A) of the LC medium comprises one or more secondpolymerisable compounds selected of formula II

P-Sp-G²  II

whereinP and Sp have the meanings given in formula I or one of the preferredmeanings given above and below for formula I, andG² is a straight-chain or branched alkyl group with 1 to 20 C atoms, ora monocyclic alkyl group with 3 to 7 C atoms, that is optionally mono-,poly- or perfluorinated and is optionally substituted by one or moregroups L as defined in formula I, and wherein one or more CH₂-groups areoptionally replaced by —O—, —CO—, —O—CO— or —CO—O— such that O-atoms arenot directly adjacent to one another.

Preferred compounds of formula II are selected from the followingformulae

P-Sp-(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)—CH₃  II1

P-Sp-(CH₂)_(n2)—(CF₂)_(n1)—CFW¹³W¹⁴  II2

wherein the individual radicals, independently of each other and on eachoccurrence identically or differently, have the following meanings

-   P, Sp have the meanings given in formula I or one of the preferred    meanings given above and below,-   W¹¹, W¹² are H, F or straight-chain or branched C₁-C₁₂-alkyl,-   W¹³, W¹⁴ are H or F,-   n1 is an integer from 2 to 15,-   n2, n3 are 0 or an integer from 1 to 3,

Very preferred compounds of formula II are selected from the followingformulae

CH₂═CW—CO—O—(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)—CH₃  II1a

CH₂═CW—CO—O—(CH₂)_(n2)—(CF₂)_(n1)—CFW¹³W¹⁴  II2a

wherein W is H, CH₃ or C₂H₅, and W¹¹, W¹², W¹³, W¹⁴, n1, n2 and n3 areas defined in formula II1 and II2, n4 is 0 or an integer from 1 to 15, sis 0 or 1, and if s is 1 then n4 is not 0.

Further preferred compounds of formula II are selected from thefollowing formulae

In another preferred embodiment of the present invention component A) ofthe LC medium comprises one or more second polymerisable compoundscomprising a polymerisable group and a bi- or polycyclic hydrocarbongroup having from 4 to 30 ring atoms, preferably from 6 to 25 ringatoms, which is preferably a non-aromatic hydrocarbon group.

Preferably component A) of the LC medium according to this preferredembodiment comprises, in addition or alternatively to the compounds offormula II, one or more second polymerisable compounds selected offormula IIA

P-Sp-G^(2A)  IIA

wherein P and Sp have the meanings given in formula I or one of thepreferred meanings given above and below for formula I, and

-   G^(2A) is a bi- or polycyclic hydrocarbon group, preferably a    bridged or fused bi- or polycyclic alkyl group, having 4 to 30 ring    atoms, preferably 6 to 25 ring atoms, which is optionally    substituted by one or more groups L.

Preferably the bi- or polycyclic hydrocarbon group or group G^(2A) is abi-, tri- or tetracyclic group.

Preferably the bi- or polycyclic hydrocarbon group or group G^(2A) is abridged bi- or polycyclic hydrocarbon group, i.e. which consists offused hydrocarbon rings, preferably fused cycloalkyl rings, where fusionoccurs across a sequence of atoms (bridgehead), preferably a bipodalbridge, like in bicyclo[2.2.1]heptane (norbornane), bicyclo[2.2.2]octaneor tricyclo[3.3.3.1]decane (adamantane).

In another preferred embodiment the present invention the bi- orpolycyclic hydrocarbon group or group G^(2A) is a fused bi- orpolycyclic hydrocarbon group, i.e. which consists of fused hydrocarbonrings, preferably fused cycloalkyl rings, where fusion occurs across abond between two atoms, like in bicyclo[3.2.0]heptane orbicyclo[4.4.0]decane (decalin).

In yet another preferred embodiment the present invention the bi- orpolycyclic hydrocarbon group or group G^(2A) is a spirocyclic group,i.e. which consists of fused hydrocarbon rings, preferably fusedcycloalkyl rings, where fusion occurs at a single atom (spiro atom),like in spiro[3.3]heptane or spiro[4.5]decane.

The bi- or polycyclic group or group G^(2A) is optionally substituted byone or more substituents, preferably selected from the group L asdefined above and below.

Preferably the bi- or polycyclic group or group G^(2A) is selected fromthe group consisting of bicyclo[1.1.1]pentyl, bicyclo[2.1.1]hexyl,bicyclo[2.2.1]heptyl (norbornyl), bicyclo[3.2.1]octyl,bicyclo[2.2.2]octyl, bicyclo[3.2.2]nonyl, bicyclo[3.3.1]nonyl,bicyclo[3.3.2]decyl, bicyclo[3.3.3]undecyl, tricyclo[3.3.3.1]decyl(adamantyl), tricyclo[5.2.1.0]decyl (tetrahydrodicyclopentadiyl),bicyclo[2.1.0]pentyl, bicyclo[2.2.0]hexyl, bicyclo[3.2.0]heptyl,bicyclo[4.2.0]octyl, bicyclo[3.3.0]octyl, bicyclo[4.3.0]nonyl,bicyclo[4.4.0]decyl (decalin), spiro[2.2]pentyl, spiro[3.2]hexyl,spiro[3.3]heptyl, spiro[4.3]octyl, spiro[4.4]nonyl, spiro[4.5]decyl, allof which are optionally substituted by one or more groups L as definedabove and below.

Very preferably the bi- or polycyclic group or group G^(2A) is selectedfrom the group consisting of bicyclo[1.1.1]pentyl, bicyclo[2.1.1]hexyl,bicyclo[2.2.1]heptyl (norbornyl), bicyclo[3.2.1]octyl,bicyclo[2.2.2]octyl, bicyclo[3.2.2]nonyl, bicyclo[3.3.1]nonyl,bicyclo[3.3.2]decyl, bicyclo[3.3.3]undecyl, tricyclo[3.3.3.1]decyl(adamantyl), all of which are optionally substituted by one or moregroups L as defined above and below.

Most preferably the bi- or polycyclic group or group G^(2A) is selectedfrom the group consisting of bicyclo[2.2.1]heptyl (norbornyl),bicyclo[2.2.2]octyl, tricyclo[3.3.3.1]decyl (adamantyl), all of whichare optionally substituted by one or more groups L as defined above andbelow.

Preferred compounds of formula IIA are selected from the followingformulae

wherein R on each occurrence identically or differently denotes P-Sp- orhas one of the meanings given for R^(x) above, and at least one of thegroups R in each of formulae IIAA-IIAC denotes P-Sp-.

Further preferred compounds of formula IIA are selected from thefollowing formulae

wherein P and Sp have the meanings given in formula IIA or one of thepreferred meanings given above, W¹¹, W¹² and W¹³ are independently ofeach other H, F or C₁-C₁₂-alkyl, preferably methyl, and the cycloalkylgroups are optionally substituted with one or more groups L as definedabove.

Very preferred compounds of formula IIA are selected from the followingformulae

wherein n is 0 or an integer from 1 to 8, W is H, CH₃ or C₂H₅ and W¹¹,W¹² and W¹³ are H, F or C₁-C₁₂-alkyl, preferably methyl.

Further preferred compounds of formula IIA are selected from thefollowing formulae

Preferably component A) of the LC medium comprises one or more thirdpolymerisable compounds selected of formula III

P¹-Sp¹-G³-Sp²-P²  III

wherein

-   P¹ and P² independently of each other independently of each other,    and on each occurrence identically or differently, denote a    polymerisable group,-   Sp¹, Sp² denote independently of each other identical or different    spacer groups or a single bond,-   G³ is a straight-chain, branched or cyclic alkyl group with 1 to 20    C atoms that is optionally mono-, poly- or perfluorinated and is    optionally substituted by one or more groups P-Sp- or L as defined    in formula I, and wherein one or more CH₂-groups are optionally    replaced by —O—, —CO—, —O—CO— or —CO—O— such that O-atoms are not    directly adjacent to one another.

P¹ and P² are preferably selected from acrylate, methacrylate,ethacrylate, and vinyloxy groups.

Further preferably one of P¹ and P² in formula III is vinyloxy and theother is acrylate, methacrylate or ethacrylate, most preferablymethacrylate.

Sp¹ and Sp² in formula III preferably denote a single bond.

If the hydrocarbon group or group G³ in the third polymerisablecompounds is a cyclic group, it is preferably a monocyclic cycloalkylgroup, which preferably has from 5 to 7 ring atoms and is optionallysubstituted by one or more groups L as defined above and below.

In another preferred embodiment of the present invention the hydrocarbongroup or group G³ in the third polymerisable compounds is a bi-, tri- ortetracyclic group, and preferably has from 4 to 30 C atoms, which isoptionally substituted by one or more groups L as defined above andbelow. Preferred bi-, tri- or tetracyclic groups or groups G³ in thethird polymerisable compound are those having one of the meanings ofgroup G^(2A) in formula IIA or its preferred meanings given above.

Preferred compounds of formula III are selected from the followingformulae

P¹-Sp¹-(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)-Sp²-P²  III1

P¹—(CH₂)_(n2)—(CF₂)_(n1)—(CH₂)_(n3)—P²  III3

(P¹-Sp¹-(CH₂)_(n4))_(n5)CH_(4-n5)  III4

wherein P¹, P², Sp¹, Sp² are as defined in formula III,

-   W¹¹ is, on each occurrence identically or differently, H, F or    C₁-C₁₂-alkyl,-   n1 is an integer from 2 to 15,-   n2, n3 are independently of each other 0 or an integer from 1 to 3,-   n4 is 0 or an integer from 1 to 15,-   n5 is 3 or 4,    and the cyclohexylene ring in formula III2 is optionally substituted    by one or more identical or different groups W¹¹.

In a preferred embodiment of the present invention the component A) ofthe LC medium comprises one or more compounds of formula III or itssubformulae wherein P¹ and P² are different polymerisable groups.

In another preferred embodiment of the present invention the componentA) of the LC medium comprises one or more compounds of formula III orits subformulae wherein P¹ and P² are identical polymerisable groups.

In the third polymerisable compounds, the polymerisable groups arepreferably selected from acrylate, methacrylate, ethacrylate andvinyloxy groups. Very preferably one of the polymerisable groups isvinyloxy and the other is acrylate or methacrylate, most preferablymethacrylate.

Very preferred compounds of formula III are selected from the followingformulae

CH₂═CW—CO—O—(CHW¹¹)_(n4)—(CH₂)_(n1)—O—CH═CH₂  III1a

CH₂═CH—O—(CHW¹)_(n4)—(CH₂)_(n1)—O—CO—CH═CH₂  III1b

CH₂═CW—CO—O—(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)—O—CO—CW═CH₂  III1c

CH₂═CW—CO—O—(CH₂)_(n2)—(CF₂)_(n1)—(CH₂)_(n3)—O—CH═CH₂  III3a

CH₂═CW—CO—O—(CH₂)_(n2)—(CF₂)_(n1)—(CH₂)_(n3)—O—CO—CW═CH₂  III3b

(CH₂═CW—CO—O—(CH₂)_(n2))₃CH  III4a

(CH₂═CW—CO—O—(CH₂)_(n2))₄C  III4b

wherein W is H, CH₃ or C₂H₅ and W¹¹, n1, n2 and n4 are as defined informula III1-III4, and the cyclohexylene ring in formula III2a-c isoptionally substituted by one or more identical or different groups W¹¹.

Further preferred compounds of formula III are selected from thefollowing formulae

Further preferred compounds of formula Ill are selected from thefollowing formulae

Further preferred compounds of formula Ill are selected from thefollowing formulae

In another preferred embodiment of the present invention component A) ofthe LC medium additionally comprises, in addition or alternatively tothe third polymerisable compounds, one or more fourth polymerisablecompounds comprising a ring system containing one or more aromatic orheteroaromatic rings or condensed aromatic or heteroaromatic rings, andattached thereto two polymerisable groups that are preferably differentfrom each other.

These compounds are preferably selected from formula IV

P¹—Sp¹-B¹—(Z^(b)—B²)_(m)-Sp²-P²  IV

in which P¹, P², Sp¹, Sp² are as defined in formula III,

-   B¹ and B² are independently of each other, and on each occurrence    identically or differently, an aromatic, heteroaromatic, alicyclic    or heterocyclic group, preferably having 4 to 25 ring atoms, which    may also contain fused rings, and which is unsubstituted, or mono-    or polysubstituted by L as defined in formula I, wherein at least    one of B¹ and B² denotes an aromatic or heteroaromatic group,-   Z^(b) is, on each occurrence identically or differently, —O—, —S—,    —CO—, —CO—O—, —OCO—, —O—CO—O—, —OCH₂—, —CH₂O—, —SCH₂—, —CH₂S—,    —CF₂O—, —OCF₂—, —CF₂S—, —SCF₂—, —(CH₂)_(n11)—, —CF₂CH₂—, —CH₂CF₂—,    —(CF₂)_(n1)—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—,    CR⁰R⁰⁰ or a single bond,-   R⁰ and R⁰⁰ each, independently of one another, denote H or alkyl    having 1 to 12 C atoms,-   m denotes 0, 1, 2, 3 or 4,-   n11 denotes 1, 2, 3 or 4,

Particularly preferred compounds of formula IV are those in which B¹ andB² each, independently of one another, denote 1,4-phenylene,1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl,phenanthrene-2,7-diyl, 9,10-dihydro-phenanthrene-2,7-diyl,anthracene-2,7-diyl, fluorene-2,7-diyl, coumarine, flavone, where, inaddition, one or more CH groups in these groups may be replaced by N,cyclohexane-1,4-diyl, in which, in addition, one or more non-adjacentCH₂ groups may be replaced by O and/or S, 1,4-cyclohexenylene,bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl,spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl,decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl,indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, where all thesegroups may be unsubstituted or mono- or polysubstituted by L as definedabove.

Very particularly preferred compounds of formula IV are those in whichB¹ and B² each, independently of one another, denote 1,4-phenylene,1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

Further preferred compounds of formula IV are selected from the groupconsisting of the following formulae:

in which P¹, P², Sp¹, Sp² and L are as defined in formula IV,

-   Z¹ is —O—, —CO—, —C(R^(y)R^(z))— or —CF₂CF₂—,-   Z², Z³ are independently of each other —CO—O—, —O—CO—, —CH₂O—,    —OCH₂—, —CF₂O—, —OCF₂— or —(CH₂)_(n11)—, where n11 is 2, 3 or 4,-   r is 0, 1, 2, 3 or 4,-   s is 0, 1, 2 or 3,-   t is 0, 1 or 2.

Especially preferred are direactive compounds of formula IV2 and IV3.

In the compounds of formulae IV1 to IV13 the group

is preferably

wherein L on each occurrence, identically or differently, has one of themeanings given above or below, and is preferably F, Cl, CN, NO₂, CH₃,C₂H₅, C(CH₃)₃, CH(CH₃)₂, CH₂CH(CH₃)C₂H₅, OCH₃, OC₂H₅, COCH₃, COC₂H₅,COOCH₃, COOC₂H₅, CF₃, OCF₃, OCHF₂, OC₂F₅ or P-Sp-, very preferably F,Cl, CN, CH₃, C₂H₅, OCH₃, COCH₃, OCF₃, more preferably F, Cl, CH₃, OCH₃,COCH₃, CF₃ over OCF₃, especially F or CH₃.

Preferred compounds of formulae IV1 to IV13 are those wherein one of P¹and P² denotes a vinyloxy group and the other denotes an acrylate,methacrylate or ethacrylate group, very preferably a methacrylate group.

Further preferred compounds of formulae IV1 to IV13 are those whereinSp¹ and Sp² are a single bond.

Further preferred compounds of formulae IV1 to IV13 are those whereinone of Sp¹ and Sp² is a single bond and the other is different from asingle bond.

Further preferred compounds of formulae IV1 to IV13 are those whereinthe group Sp¹ and Sp³ that is different from a single bond is—(CH₂)_(s1)—X″—, wherein s1 is an integer from 1 to 6, preferably 2, 3,4 or 5, and X″ is X″ is the linkage to the benzene ring and is —O—,—O—CO—, —CO—O, —O—CO—O— or a single bond.

Very preferred compounds of formula IV are selected from the groupconsisting of the following formulae:

The concentration of the first polymerisable compounds, especially thoseof formula I, in the LC medium is preferably from 0.5 to 20%, verypreferably from 1 to 18%, most preferably from 2 to 15%.

The concentration of the second polymerisable compounds, especiallythose of formula II, in the LC medium is preferably from 0.5 to 15%,very preferably from 1 to 12%, most preferably from 2 to 10%.

The concentration of the third polymerisable compounds, especially thoseof formula III, in the LC medium is preferably from 0.05 to 5%, verypreferably from 0.1 to 3%, most preferably from 0.2 to 2%.

The concentration of the fourth polymerisable compounds, especiallythose of formula IV, in the LC medium is preferably from 0.05 to 5%,very preferably from 0.1 to 3%, most preferably from 0.2 to 2%.

The total concentration of the first, second, third and fourthpolymerisable compounds, especially those of formula I, II, III and IV,in the LC medium is preferably from 1 to 30% by weight, very preferablyfrom 1 to 25% by weight.

In a first preferred embodiment of the present invention, the totalconcentration of the first, second, third and fourth polymerisablecompounds, especially those of formula I, II, III and IV, in the LCmedium is from 10 to 20% by weight.

In a second preferred embodiment of the present invention, the totalconcentration of the first, second, third and fourth polymerisablecompounds, especially those of formula I, II, III and IV, in the LCmedium is from 5 to 10% by weight.

In a third preferred embodiment of the present invention, the totalconcentration of the first, second, third and fourth polymerisablecompounds, especially those of formula I, II, III and IV, in the LCmedium is from 1 to 5% by weight.

The ratio of first polymerisable compounds or compounds of formula I,and second polymerisable compounds or compounds of formula II, in the LCmedium is preferably from 50:1 to 1:50, very preferably from 10:1 to1:10, most preferably from 4:1 to 1:4.

The total concentration of first and second polymerisable compounds with(exactly) one polymerisable group, or compounds of formula I and II, inthe LC medium is preferably from 5 to 30% by weight.

The total concentration of third and fifth polymerisable compounds with(exactly) two polymerisable groups, or compounds of formula III and IV,in the LC medium is preferably from 0.1 to 10%, very preferably from 0.1to 5%, most preferably from 0.1 to 2% by weight.

Particular preference is given to LC media wherein the polymerisablecomponent A) comprises one, two or three first polymerisable compounds,preferably of formula I, one, two or three second polymerisablecompounds, preferably of formula II, one, two or three thirdpolymerisable compounds, preferably of formula III, and optionally one,two or three fourth polymerisable compounds, preferably of formula IV.

Besides the polymerisable component A) as described above, the LC mediumaccording to the present invention comprises an LC component B), or LChost mixture, comprising one or more, preferably two or more LCcompounds which are selected from low-molecular-weight compounds thatare unpolymerisable. These LC compounds are selected such that theystable and/or unreactive to a polymerisation reaction under theconditions applied to the polymerisation of the polymerisable compounds.

Preference is given to LC media in which the LC component B), or the LChost mixture, has a nematic LC phase, and preferably has no chiralliquid crystal phase. The LC component B), or LC host mixture, ispreferably a nematic LC mixture.

Preference is furthermore given to achiral polymerisable compounds, andto LC media in which the compounds of component A) and/or B) areselected exclusively from the group consisting of achiral compounds.

Preferably the proportion of the LC component B) in the LC medium isfrom 70 to 95% by weight.

The LC media and LC host mixtures of the present invention preferablyhave a nematic phase range ≥80 K, very preferably ≥100 K, and preferablya rotational viscosity ≤250 mPa·s, very preferably ≤200 mPa·s, at 20° C.

The birefringence Δn of LC media and LC host mixtures according to theinvention is preferably from 0.07 to 0.15, particularly preferably from0.08 to 0.15.

In a first preferred embodiment of the present invention, the LC mediumcontains an component B) or LC host mixture having a positive dielectricanisotropy Δε.

Such LC media are especially suitable for use in TN, OCB-, Posi-VA-,IPS- or FFS-displays or related modes using LC-materials with Δε>0.

The LC media and LC host mixtures according to this first preferredembodiment preferably have a positive dielectric anisotropy Δε from +2to +30, particularly preferably from +3 to +20, at 20° C. and 1 kHz.

Particularly preferred is an LC medium of this first preferredembodiment, wherein the liquid-crystalline component B) or LC hostmixture comprises one or more compounds selected from formula A and B

in which the individual radicals have, independently of each other andon each occurrence identically or differently, the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

-   R²¹, R³¹ each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   X⁰ F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   Z³¹ —CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O— or    a single bond, preferably —CH₂CH₂—, —COO—, trans-CH═CH— or a single    bond, particularly preferably —COO—, trans-CH═CH— or a single bond,-   L²¹, L²², L³¹, L³² each, independently of one another, H or F,-   g 0, 1, 2 or 3.

In the compounds of formula A and B, X⁰ is preferably F, Cl, CF₃, CHF₂,OCF₃, OCHF₂, OCFHCF₃, OCFHCHF₂, OCFHCHF₂, OCF₂CH₃, OCF₂CHF₂, OCF₂CHF₂,OCF₂CF₂CHF₂, OCF₂CF₂CHF₂, OCFHCF₂CF₃, OCFHCF₂CHF₂, OCF₂CF₂CF₃,OCF₂CF₂CClF₂, OCClFCF₂CF₃ or CH═CF₂, very preferably F or OCF₃, mostpreferably F.

In the compounds of formula A and B, R²¹ and R³¹ are preferably selectedfrom straight-chain alkyl or alkoxy with 1, 2, 3, 4, 5 or 6 C atoms, andstraight-chain alkenyl with 2, 3, 4, 5, 6 or 7 C atoms.

In the compounds of formula A and B, g is preferably 1 or 2.

In the compounds of formula B, Z³¹ is preferably COO, trans-CH═CH or asingle bond, very preferably COO or a single bond.

Preferably component B) of the LC medium comprises one or more compoundsof formula A selected from the group consisting of the followingformulae:

in which A²¹, R²¹, X⁰, L²¹ and L²² have the meanings given in formula A,L²³ and L²⁴ each, independently of one another, are H or F, and X⁰ ispreferably F. Particularly preferred are compounds of formulae A1 andA2.

Particularly preferred compounds of formula A1 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula A1, L²³,L²⁴, L²⁵ and L²⁶ are each, independently of one another, H or F, and X⁰is preferably F.

Very particularly preferred compounds of formula A1 are selected fromthe group consisting of the following subformulae:

in which R²¹ is as defined in formula A1.

Particularly preferred compounds of formula A2 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula A2, L²³,L²⁴, L²⁵ and L²⁶ each, independently of one another, are H or F, and X⁰is preferably F.

Very particularly preferred compounds of formula A2 are selected fromthe group consisting of the following subformulae:

in which R²¹ and X⁰ are as defined in formula A2.

Particularly preferred compounds of formula A3 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula A3, andX⁰ is preferably F.

Particularly preferred compounds of formula A4 are selected from thegroup consisting of the following subformulae:

in which R²¹ is as defined in formula A4.

Preferably component B) of the LC medium comprises one or more compoundsof formula B selected from the group consisting of the followingformulae:

in which g, A³¹, A³², R³¹, X⁰, L³¹ and L³² have the meanings given informula B, and X⁰ is preferably F. Particularly preferred are compoundsof formulae B1 and B2.

Particularly preferred compounds of formula B1 are selected from thegroup consisting of the following subformulae:

in which R³¹, X⁰, L³¹ and L³² have the meaning given in formula B1, andX⁰ is preferably F.

Very particularly preferred compounds of formula B1a are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B1.

Very particularly preferred compounds of formula B1b are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B1.

Particularly preferred compounds of formula B2 are selected from thegroup consisting of the following subformulae:

in which R³¹, X⁰, L³¹ and L³² have the meaning given in formula B2, L³³,L³⁴, L³⁵ and L³⁶ are each, independently of one another, H or F, and X⁰is preferably F.

Very particularly preferred compounds of formula B2 are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2b are selected fromthe group consisting of the following subformulae

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2c are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2d and B2e areselected from the group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2f are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2g are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2h are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2i are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2k are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B21 are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Alternatively to, or in addition to, the compounds of formula B1 and/orB2 component B) of the LC medium may also comprise one or more compoundsof formula B3 as defined above.

Particularly preferred compounds of formula B3 are selected from thegroup consisting of the following subformulae:

in which R³¹ is as defined in formula B3.

Preferably component B) of the LC medium comprises, in addition to thecompounds of formula A and/or B, one or more compounds of formula C

in which the individual radicals have the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

-   R⁴¹, R⁴² each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   Z⁴¹, Z⁴² each, independently of one another, —CH₂CH₂—, —COO—,    trans-CH═CH—, trans-CF═CF—, —CH₂O—, —CF₂O—, —C≡C— or a single bond,    preferably a single bond,-   h 0, 1, 2 or 3.

In the compounds of formula C, R⁴¹ and R⁴² are preferably selected fromstraight-chain alkyl or alkoxy with 1, 2, 3, 4, 5 or 6 C atoms, andstraight-chain alkenyl with 2, 3, 4, 5, 6 or 7 C atoms.

In the compounds of formula C, h is preferably 0, 1 or 2.

In the compounds of formula C, Z⁴¹ and Z⁴² are preferably selected fromCOO, trans-CH═CH and a single bond, very preferably from COO and asingle bond.

Preferred compounds of formula C are selected from the group consistingof the following subformulae:

wherein R⁴¹ and R⁴² have the meanings given in formula C, and preferablydenote each, independently of one another, alkyl, alkoxy, fluorinatedalkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy,alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms.

In another preferred embodiment of the present invention component B) ofthe LC medium comprises, in addition to the compounds of formula Aand/or B, one or more compounds of formula D

in which A41, A⁴², Z⁴¹, Z⁴², R⁴¹, R⁴² and h have the meanings given informula C or one of the preferred meanings given above.

Preferred compounds of formula D are selected from the group consistingof the following subformulae:

in which R⁴¹ and R⁴² have the meanings given in formula D and R⁴¹preferably denotes alkyl bedeutet, and in formula D1 R⁴² preferablydenotes alkenyl, particularly preferably —(CH₂)₂—CH═CH—CH₃, and informula D2 R⁴² preferably denotes alkyl, —(CH₂)₂—CH═CH₂ or—(CH₂)₂—CH═CH—CH₃.

In another preferred embodiment of the present invention component B) ofthe LC medium comprises, in addition to the compounds of formula Aand/or B, one or more compounds of formula E containing an alkenyl group

in which the individual radicals, on each occurrence identically ordifferently, each, independently of one another, have the followingmeaning:

-   R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the    rings X, Y and Z denotes cyclohexenyl, also one of the meanings of    R^(A2),-   R^(A2) alkyl having 1 to 12 C atoms, in which, in addition, one or    two non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,    —OCO— or —COO— in such a way that O atoms are not linked directly to    one another,-   x 1 or 2.

R^(A2) is preferably straight-chain alkyl or alkoxy having 1 to 8 Catoms or straight-chain alkenyl having 2 to 7 C atoms.

Preferred compounds of formula E are selected from the followingsub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very preferred compounds of the formula E are selected from thefollowing sub-formulae:

in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, andR^(b1) denotes H, CH₃ or C₂H₅.

Very particularly preferred compounds of the formula E are selected fromthe following sub-formulae:

Most preferred are compounds of formula E1a2, E1a5, E3a1 and E6a1.

In another preferred embodiment of the present invention component B) ofthe LC medium comprises, in addition to the compounds of formula Aand/or B, one or more compounds of formula F

in which the individual radicals have, independently of each other andon each occurrence identically or differently, the following meanings:

-   R²¹, R³¹ each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   X⁰ F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   Z²¹ —CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O—,    —CF₂O—, —C≡C— or a single bond, preferably —CF₂O—,-   L²¹, L²², L²³, L²⁴ each, independently of one another, H or F,-   g 0, 1, 2 or 3.

Particularly preferred compounds of formula F are selected from thegroup consisting of the following formulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula F, L²⁵and L²⁶ are each, independently of one another, H or F, and X⁰ ispreferably F.

Very particularly preferred compounds of formula F1-F3 are selected fromthe group consisting of the following subformulae:

in which R²¹ is as defined in formula F1.

In another preferred embodiment of the present invention component B) ofthe LC medium comprises, in addition to the compounds of formula Aand/or

B, one or more compounds of formula G containing a cyano group.

in which the individual radicals have the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

-   R⁵¹, R⁵² each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   Z⁵¹, Z⁴² —CH₂CH₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O—,    —CF₂O—, —C≡C— or a single bond, preferably a single bond,-   L⁵¹, L⁵² each, independently of one another, H or F,-   i 0, 1, 2 or 3.

Preferred compounds of formula G are selected from the followingsubformulae

in which R⁵¹ is as defined in formula G and L¹ and L² are each,independently of one another, H or F.

Very preferred are compounds of formula G1, G2 and G5.

Preferred compounds of formula G1-G9 are those wherein L⁵¹ and L⁵² areF.

Further preferred compounds of formula G1-G7 are those wherein L⁵¹ is Fand L⁵² is H.

Very preferred compounds of formula G are selected from the groupconsisting of the following subformulae:

in which R⁵¹ is as defined in formula G.

In the compounds of formula G, G1-G7 and their subformulae, R⁵¹ isparticularly preferably alkyl or alkoxy having 1 to 8 carbon atoms, oralkenyl having from 2 to 7 carbon atoms.

The concentration of the compounds of formula A and B in the LC hostmixture is preferably from 2 to 60%, very preferably from 3 to 45%, mostpreferably from 4 to 35%.

The concentration of the compounds of formula C and D in the LC hostmixture is preferably from 2 to 70%, very preferably from 5 to 65%, mostpreferably from 10 to 60%.

The concentration of the compounds of formula E in the LC host mixtureis preferably from 5 to 50%, very preferably from 5 to 35%.

The concentration of the compounds of formula F in the LC host mixtureis preferably from 2 to 30%, very preferably from 5 to 20%.

Further preferred embodiments of the present invention are listed below,including any combination thereof.

-   a) The LC host mixture comprises one or more compounds of formula A    and/or B with high positive dielectric anisotropy, preferably with    Δε>15.-   b) The LC host mixture comprises one or more compounds selected from    the group consisting of formulae A1a2, A1b1, A1d1, A1f1, A2a1, A2h1,    A2l1, A2l2, A2k1, B2h3, B2l1, F1a. The proportion of these compounds    in the LC host mixture is preferably from 4 to 40%, very preferably    from 5 to 35%.-   c) The LC host mixture comprises one or more compounds selected from    the group consisting of formulae C3, C4, C5, C9 and D2. The    proportion of these compounds in the LC host mixture is preferably    from 8 to 70%, very preferably from 10 to 60%.-   d) The LC host mixture comprises one or more compounds selected from    the group consisting of formulae G1, G2 and G5, preferably G1a, G2a    and G5a. The proportion of these compounds in the LC host mixture is    preferably from 4 to 40%, very preferably from 5 to 35%.-   e) The LC host mixture comprises one or more compounds selected from    the group consisting of formulae E1, E3 and E6, preferably E1a, E3a    and E6a, very preferably E1a2, E1a5, E3a1 and E6a1. The proportion    of these compounds in the LC host mixture is preferably from 5 to    60%, very preferably from 10 to 50%.

In a second preferred embodiment of the present invention, the LC mediumcontains an component B) or LC host mixture having a negative dielectricanisotropy Δε.

Such LC media are especially suitable for use in VA, IPS and UB-FFSdisplays or related modes using LC-materials with Δε<0.

The LC media and LC host mixtures according to this second preferredembodiment preferably have a negative dielectric anisotropy Δε from −0.5to −10, very preferably from −2.5 to −7.5, at 20° C. and 1 kHz.

Particularly preferred embodiments of an LC medium according to thissecond preferred embodiment are those of sections a)-z2) below:

-   a) LC medium wherein the component B) or LC host mixture comprises    one or more compounds selected from formulae CY and PY:

whereina denotes 1 or 2,b denotes 0 or 1,

-   R¹ and R² each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,-   Z^(x) and Z^(y) each, independently of one another, denote —CH₂CH₂—,    —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—, —C₂F₄—,    —CF═CF—, —CH═CH—CH₂O— or a single bond, preferably a single bond,-   L¹⁻⁴ each, independently of one another, denote F, Cl, OCF₃, CF₃,    CH₃, CH₂F, CHF₂.

Preferably, both L¹ and L² denote F or one of L¹ and L² denotes F andthe other denotes Cl, or both L³ and L⁴ denote F or one of L³ and L⁴denotes F and the other denotes Cl.

The compounds of the formula CY are preferably selected from the groupconsisting of the following sub-formulae:

in which a denotes 1 or 2, alkyl and alkyl* each, independently of oneanother, denote a straight-chain alkyl radical having 1-6 C atoms, andalkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and(O) denotes an oxygen atom or a single bond. Alkenyl preferably denotesCH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Especially preferred are compounds selected from formulae CY2, CY8, CY10and CY16.

The compounds of the formula PY are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms, and (O) denotes anoxygen atom or a single bond. Alkenyl preferably denotes CH₂═CH—,CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Especially preferred are compounds selected from formulae PY2, PY8, PY10and PY16.

Preferably the concentration of the compounds of formula CY and PY andtheir subformulae in the LC medium is from 10 to 70% by weight, verypreferably from 15 to 50% by weight.

Preferably the concentration of the compounds of formula CY and itssubformulae in the LC medium is from 2 to 40% by weight, very preferablyfrom 3 to 30% by weight.

Preferably the concentration of the compounds of formula PY and itssubformulae in the LC medium is from 2 to 50% by weight, very preferablyfrom 3 to 40% by weight.

-   b) LC medium wherein the component B) or LC host mixture comprises    one or more mesogenic or LC compounds comprising an alkenyl group    (hereinafter also referred to as “alkenyl compounds”), wherein said    alkenyl group is stable to a polymerisation reaction under the    conditions used for polymerisation of the polymerisable compounds    contained in the LC medium.

Preferably the component B) or LC host mixture comprises one or morealkenyl compounds selected from formulae AN and AY

in which the individual radicals, on each occurrence identically ordifferently, and each, independently of one another, have the followingmeaning:

-   R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the    rings X, Y and Z denotes cyclohexenyl, also one of the meanings of    R^(A2),-   R^(A2) alkyl having 1 to 12 C atoms, in which, in addition, one or    two non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,    —OCO— or —COO— in such a way that O atoms are not linked directly to    one another,-   Z^(x) —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—,    —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O—, or a single bond, preferably    a single bond,-   L^(1,2) H, F, Cl, OCF₃, CF₃, CH₃, CH₂F or CHF₂H, preferably H, F or    Cl,-   x 1 or 2,-   z 0 or 1.

Preferred compounds of formula AN and AY are those wherein R^(A2) isselected from ethenyl, propenyl, butenyl, pentenyl, hexenyl andheptenyl.

In a preferred embodiment the component B) or LC host mixture comprisesone or more compounds of formula AN selected from the followingsub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Preferably the component B) or LC host mixture comprises one or morecompounds selected from formulae AN1, AN2, AN3 and AN6, very preferablyone or more compounds of formula AN1.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds of formula AN selected from thefollowing sub-formulae:

in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, andR^(b1) denotes H, CH₃ or C₂H₅.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds selected from the followingsub-formulae:

Most preferred are compounds of formula AN1a2 and AN1a5.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds of formula AY selected from thefollowing sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, “(O)” denotes an O-atomor a single bond, and alkenyl and alkenyl* each, independently of oneanother, denote a straight-chain alkenyl radical having 2-7 C atoms.Alkenyl and alkenyl* preferably denote CH₂═CH—, CH₂═CHCH₂CH₂—,CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds of formula AY selected from thefollowing sub-formulae:

in which m and n each, independently of one another, denote 1, 2, 3, 4,5 or 6, and alkenyl denotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

Preferably the proportion of compounds of formula AN and AY in the LCmedium is from 2 to 70% by weight, very preferably from 5 to 60% byweight, most preferably from 10 to 50% by weight.

Preferably the LC medium or LC host mixture contains 1 to 5, preferably1, 2 or 3 compounds selected from formulae AN and AY.

In another preferred embodiment of the present invention the LC mediumcomprises one or more compounds of formula AY14, very preferably ofAY14a. The proportion of compounds of formula AY14 or AY14a in the LCmedium is preferably 3 to 20% by weight.

The addition of alkenyl compounds of formula AN and/or AY enables areduction of the viscosity and response time of the LC medium.

-   c) LC medium wherein the component B) or LC host mixture comprises    one or more compounds of the following formula:

in which the individual radicals have the following meanings:

-   R³ and R⁴ each, independently of one another, denote alkyl having 1    to 12 C atoms, in which, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in    such a way that O atoms are not linked directly to one another,-   Z^(y) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,    —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,    preferably a single bond.

The compounds of the formula ZK are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Especially preferred are compounds of formula ZK1.

Particularly preferred compounds of formula ZK are selected from thefollowing sub-formulae:

wherein the propyl, butyl and pentyl groups are straight-chain groups.

Most preferred are compounds of formula ZK1a.

-   d) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of the following    formula:

in which the individual radicals on each occurrence, identically ordifferently, have the following meanings:

-   R⁵ and R⁶ each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,

ande denotes 1 or 2.

The compounds of the formula DK are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

-   e) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of the following    formula:

in which the individual radicals have the following meanings:

with at least one ring F being different from cyclohexylene,f denotes 1 or 2,

-   R¹ and R² each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,-   Z^(x) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,    —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,    preferably a single bond,-   L¹ and L² each, independently of one another, denote F, Cl, OCF₃,    CF₃, CH₃, CH₂F, CHF₂.

Preferably, both radicals L¹ and L² denote F or one of the radicals L¹and L² denotes F and the other denotes Cl.

The compounds of the formula LY are preferably selected from the groupconsisting of the following sub-formulae:

in which R¹ has the meaning indicated above, alkyl denotes astraight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygenatom or a single bond, and v denotes an integer from 1 to 6. R¹preferably denotes straight-chain alkyl having 1 to 6 C atoms orstraight-chain alkenyl having 2 to 6 C atoms, in particular CH₃, C₂H₅,n-C₃H₇, n-C₄H₉, n-C₅H₁₁, CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

-   f) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which alkyl denotes C₁₋₆-alkyl, Lx denotes H or F, and X denotes F,CI, OCF₃, OCHF₂ or OCH═CF₂. Particular preference is given to compoundsof the formula G1 in which X denotes F.

-   g) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which R⁵ has one of the meanings indicated above for R¹, alkyldenotes C₁₋₆-alkyl, d denotes 0 or 1, and z and m each, independently ofone another, denote an integer from 1 to 6. R⁵ in these compounds isparticularly preferably C₁₋₆-alkyl or -alkoxy or C₂₋₆-alkenyl, d ispreferably 1. The LC medium according to the invention preferablycomprises one or more compounds of the above-mentioned formulae inamounts of ≥5% by weight.

-   h) LC medium wherein component B) or the LC host mixture    additionally comprises one or more biphenyl compounds selected from    the group consisting of the following formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

The proportion of the biphenyls of the formulae B1 to B3 in the LC hostmixture is preferably at least 3% by weight, in particular 5% by weight.

The compounds of the formula B2 are particularly preferred.

The compounds of the formulae B1 to B3 are preferably selected from thegroup consisting of the following sub-formulae:

in which alkyl* denotes an alkyl radical having 1-6 C atoms. The mediumaccording to the invention particularly preferably comprises one or morecompounds of the formulae B1a and/or B2c.

-   i) LC medium wherein component B) or the LC host mixture    additionally comprises one or more terphenyl compounds of the    following formula:

in which R⁵ and R⁶ each, independently of one another, have one of themeanings indicated above, and

each, independently of one another, denote

in which L⁵ denotes F or Cl, preferably F, and L⁶ denotes F, Cl, OCF₃,CF₃, CH₃, CH₂F or CHF₂, preferably F.

The compounds of the formula T are preferably selected from the groupconsisting of the following sub-formulae:

in which R denotes a straight-chain alkyl or alkoxy radical having 1-7 Catoms, R* denotes a straight-chain alkenyl radical having 2-7 C atoms,(O) denotes an oxygen atom or a single bond, and m denotes an integerfrom 1 to 6. R* preferably denotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

R preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl,methoxy, ethoxy, propoxy, butoxy or pentoxy.

The LC host mixture according to the invention preferably comprises theterphenyls of the formula T and the preferred sub-formulae thereof in anamount of 0.5-30% by weight, in particular 1-20% by weight.

Particular preference is given to compounds of the formulae T1, T2, T3and T21. In these compounds, R preferably denotes alkyl, furthermorealkoxy, each having 1-5 C atoms.

The terphenyls are preferably employed in LC media according to theinvention if the Δn value of the mixture is to be 0.1. Preferred LCmedia comprise 2-20% by weight of one or more terphenyl compounds of theformula T, preferably selected from the group of compounds T1 to T22.

-   k) LC medium wherein component B) or the LC host mixture    additionally comprises one or more quaterphenyl compounds selected    from the group consisting of the following formulae:

wherein

-   R^(Q) is alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C    atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which    are optionally fluorinated,-   X^(Q) is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   L^(Q1) to L^(Q6) independently of each other are H or F, with at    least one of L^(Q1) to L^(Q6) being F.

Preferred compounds of formula Q are those wherein R^(Q) denotesstraight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl,n-propyl or n-butyl.

Preferred compounds of formula Q are those wherein L^(Q3) and L^(Q4) areF. Further preferred compounds of formula Q are those wherein L^(Q3),L^(Q4) and one or two of L^(Q1) and L^(Q2) are F.

Preferred compounds of formula Q are those wherein X^(Q) denotes F orOCF₃, very preferably F.

The compounds of formula Q are preferably selected from the followingsubformulae

wherein R^(Q) has one of the meanings of formula Q or one of itspreferred meanings given above and below, and is preferably ethyl,n-propyl or n-butyl.

Especially preferred are compounds of formula Q1, in particular thosewherein R^(Q) is n-propyl.

Preferably the proportion of compounds of formula Q in the LC hostmixture is from >0 to ≤5% by weight, very preferably from 0.1 to 2% byweight, most preferably from 0.2 to 1.5% by weight.

Preferably the LC host mixture contains 1 to 5, preferably 1 or 2compounds of formula Q.

The addition of quaterphenyl compounds of formula Q to the LC hostmixture enables to reduce ODF mura, whilst maintaining high UVabsorption, enabling quick and complete polymerisation, enabling strongand quick tilt angle generation, and increasing the UV stability of theLC medium.

Besides, the addition of compounds of formula Q, which have positivedielectric anisotropy, to the LC medium with negative dielectricanisotropy allows a better control of the values of the dielectricconstants ε_(∥) and ε_(⊥), and in particular enables to achieve a highvalue of the dielectric constant ε_(∥) while keeping the dielectricanisotropy Δε constant, thereby reducing the kick-back voltage andreducing image sticking.

-   l) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of formula CC:

whereinR^(C) denotes alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 Catoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which areoptionally fluorinated,X^(C) denotes F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atomsor halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,L^(C1), L^(C2) independently of each other denote H or F, with at leastone of L^(C1) and L^(C2) being F.

Preferred compounds of formula CC are those wherein R^(C) denotesstraight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl,n-propyl or n-butyl.

Preferred compounds of formula CC are those wherein L^(C1) and L^(C2)are F.

Preferred compounds of formula CC are those wherein X^(C) denotes F orOCF₃, very preferably F.

Preferred compounds of formula CC are selected from the followingformula

wherein R^(C) has one of the meanings of formula CC or one of itspreferred meanings given above and below, and is preferably ethyl,n-propyl or n-butyl, very preferably n-propyl.

Preferably the proportion of compounds of formula CC in the LC hostmixture is from >0 to ≤10% by weight, very preferably from 0.1 to 8% byweight, most preferably from 0.2 to 5% by weight.

Preferably the LC host mixture contains 1 to 5, preferably 1, 2 or 3compounds of formula CC.

The addition of compounds of formula CC, which have positive dielectricanisotropy, to the LC medium with negative dielectric anisotropy allowsa better control of the values of the dielectric constants ε_(∥) andε_(⊥), and in particular enables to achieve a high value of thedielectric constant ε_(∥) while keeping the dielectric anisotropy Δεconstant, thereby reducing the kick-back voltage and reducing imagesticking. Besides, the addition of compounds of formula CC enables toreduce the viscosity and the response time of the LC medium.

-   m) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which R¹ and R² have the meanings indicated above and preferablyeach, independently of one another, denote straight-chain alkyl having 1to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

Preferred media comprise one or more compounds selected from theformulae O1, O3 and O4.

-   n) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of the following    formula:

in which

R⁹ denotes H, CH₃, C₂H₅ or n-C₃H₇, (F) denotes an optional fluorinesubstituent, and q denotes 1, 2 or 3, and R⁷ has one of the meaningsindicated for R¹, preferably in amounts of >3% by weight, in particular≥5% by weight and very particularly preferably 5-30% by weight.

Particularly preferred compounds of the formula FI are selected from thegroup consisting of the following sub-formulae:

in which R⁷ preferably denotes straight-chain alkyl, and R⁹ denotes CH₃,C₂H₅ or n-C₃H₇. Particular preference is given to the compounds of theformulae FI1, FI2 and FI3.

-   o) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which R⁸ has the meaning indicated for R¹, and alkyl denotes astraight-chain alkyl radical having 1-6 C atoms.

-   p) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds which contain a    tetrahydronaphthyl or naphthyl unit, such as, for example, the    compounds selected from the group consisting of the following    formulae:

in which

-   R¹⁰ and R¹¹ each, independently of one another, denote alkyl having    1 to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,    and R¹⁰ and R¹¹ preferably denote straight-chain alkyl or alkoxy    having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C    atoms, and-   Z¹ and Z² each, independently of one another, denote —C₂H₄—,    —CH═CH—, —(CH₂)₄—, —(CH₂)₃O—, —O(CH₂)₃—, —CH═CH—CH₂CH₂—,    —CH₂CH₂CH═CH—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—,    —CF═CH—, —CH═CF—, —CH₂— or a single bond.-   q) LC medium wherein component B) or the LC host mixture    additionally comprises one or more difluorodibenzochromans and/or    chromans of the following formulae:

in which

-   R¹¹ and R¹² each, independently of one another, have one of the    meanings indicated above for R¹¹,-   ring M is trans-1,4-cyclohexylene or 1,4-phenylene,-   Z^(m) —C₂H₄—, —CH₂O—, —OCH₂—, —CO—O— or —O—CO—,-   c is 0, 1 or 2,    preferably in amounts of 3 to 20% by weight, in particular in    amounts of 3 to 15% by weight.

Particularly preferred compounds of the formulae BC, CR and RC areselected from the group consisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygenatom or a single bond, c is 1 or 2, and alkenyl and alkenyl* each,independently of one another, denote a straight-chain alkenyl radicalhaving 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH₂═CH—,CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very particular preference is given to LC host mixtures comprising one,two or three compounds of the formula BC-2.

-   r) LC medium wherein component B) or the LC host mixture    additionally comprises one or more fluorinated phenanthrenes and/or    dibenzofurans of the following formulae:

in which R¹¹ and R¹² each, independently of one another, have one of themeanings indicated above for R¹¹, b denotes 0 or 1, L denotes F, and rdenotes 1, 2 or 3.

Particularly preferred compounds of the formulae PH and BF are selectedfrom the group consisting of the following sub-formulae:

in which R and R′ each, independently of one another, denote astraight-chain alkyl or alkoxy radical having 1-7 C atoms.

-   s) LC medium wherein component B) or the LC host mixture    additionally comprises one or more monocyclic compounds of the    following formula

wherein

-   R¹ and R² each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,-   L¹ and L² each, independently of one another, denote F, Cl, OCF₃,    CF₃, CH₃, CH₂F, CHF₂.

Preferably, both L¹ and L² denote F or one of L¹ and L² denotes F andthe other denotes Cl,

The compounds of the formula Y are preferably selected from the groupconsisting of the following sub-formulae:

in which, Alkyl and Alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes astraight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl*each, independently of one another, denote a straight-chain alkenylradical having 2-6 C atoms. Alkenyl and Alkenyl* preferably denoteCH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Particularly preferred compounds of the formula Y are selected from thegroup consisting of the following sub-formulae:

wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5C atoms.

-   t) LC medium which, apart from the polymerisable compounds as    described above and below, does not contain a compound which    contains a terminal vinyloxy group (—O—CH═CH₂).-   u) LC medium wherein component B) or the LC host mixture comprises 1    to 8, preferably 1 to 5, compounds of the formulae CY1, CY2, PY1    and/or PY2. The proportion of these compounds in the LC host mixture    as a whole is preferably 5 to 60%, particularly preferably 10 to    35%. The content of these individual compounds is preferably in each    case 2 to 20%.-   v) LC medium wherein component B) or the LC host mixture comprises 1    to 8, preferably 1 to 5, compounds of the formulae CY9, CY10, PY9    and/or PY10. The proportion of these compounds in the LC host    mixture as a whole is preferably 5 to 60%, particularly preferably    10 to 35%. The content of these individual compounds is preferably    in each case 2 to 20%.-   w) LC medium wherein component B) or the LC host mixture comprises 1    to 10, preferably 1 to 8, compounds of the formula ZK, in particular    compounds of the formulae ZK1, ZK2 and/or ZK6. The proportion of    these compounds in the LC host mixture as a whole is preferably 3 to    25%, particularly preferably 5 to 45%. The content of these    individual compounds is preferably in each case 2 to 20%.-   x) LC medium in which the proportion of compounds of the formulae    CY, PY and ZK in the LC host mixture as a whole is greater than 70%,    preferably greater than 80%.-   y) LC medium in which the LC host mixture contains one or more    compounds containing an alkenyl group, preferably selected from    formulae AN and AY, very preferably selected from formulae AN1, AN3,    AN6 and AY14, most preferably from formulae AN1a, AN3a, AN6a and    AY14. The concentration of these compounds in the LC host mixture is    preferably from 2 to 70%, very preferably from 3 to 55%.-   z) LC medium wherein component B) or the LC host mixture contains    one or more, preferably 1 to 5, compounds selected of formula    PY1-PY8, very preferably of formula PY2. The proportion of these    compounds in the LC host mixture as a whole is preferably 1 to 30%,    particularly preferably 2 to 20%. The content of these individual    compounds is preferably in each case 1 to 20%.-   z1) LC medium wherein component B) or the LC host mixture contains    one or more, preferably 1, 2 or 3, compounds selected from formulae    T1, T2, T3 and T21, very preferably from formula T2. The content of    these compounds in the LC host mixture as a whole is preferably 1 to    20%.-   z2) LC medium in which the LC host mixture contains one or more,    preferably 1, 2 or 3, compounds of formula BF1, and one or more,    preferably 1, 2 or 3, compounds selected from formulae AY14, AY15    and AY16, very preferably of formula AY14. The proportion of the    compounds of formula AY14-AY16 in the LC host mixture is preferably    from 2 to 35%, very preferably from 3 to 30%. The proportion of the    compounds of formula BF1 in the LC host mixture is preferably from    0.5 to 20%, very preferably from 1 to 15%. Further preferably the LC    host mixture according to this preferred embodiment contains one or    more, preferably 1, 2 or 3 compounds of formula T, preferably    selected from formula T1, T2 and T3, very preferably from formula    T2. The proportion of the compounds of formula T in the LC host    mixture medium is preferably from 0.5 to 15%, very preferably from 1    to 10%.

In the LC medium according to the present invention, the use of an LChost mixture together with the use of a polymerisable componentcomprising a combination of a first, second and third polymerisablecompound as described above leads to advantageous properties in LCdisplays. In particular, one or more of the following advantages couldbe achieved:

-   -   easy and quick formation of polymer walls by        polymerisation-induced phase separation of the polymer formed by        the first and second polymerisable compounds,    -   formation of polymer walls with highly defined shape and        constant thickness,    -   constant cell gap,    -   high flexibility of the display cell in case plastic substrates        are used,    -   high resistance of the display cell against mechanical pressure,        and low variation of the cell gap under pressure,    -   good adhesion of the polymer walls to the substrates,    -   low number of defects,    -   reduced formation of domains with different electrooptical        properties like response time or contrast,    -   high transparency,    -   good contrast,    -   fast response times.

The display manufacture process is known to the skilled person and isdescribed in the literature, for example in U.S. Pat. No. 6,130,738 andEP2818534 A1.

The present invention also relates to a process for the production of anLC display as described above and below, comprising the steps ofproviding an LC medium as described above and below into the display,and polymerising the polymerisable compounds in defined regions of thedisplay.

Preferably the polymerisable compounds are photopolymerised by exposureto UV irradiation.

Further preferably the polymerisable compounds are photopolymerised byexposure to UV irradiation through a photomask. The UV radiation can begenerated by a variety of light sources which are known to the skilledperson, including but not limited to arc lamps, led lights, laser lightsources, or others.

The photomask is preferably designed such that it comprises regions thatare transparent to the UV radiation used for photopolymerisation, andregions that are not transparent to the UV radiation used forphotopolymerisation, and wherein the transparent regions form a patternor image that corresponds to the desired shape of the polymer walls. Asa result the polymerisable compounds are only polymerised in those partsof the display that are covered by the transparent regions of thephotomask, thus forming polymer walls of the desired shape.

Alternatively to using a photomask, a light source can be used thatemits light with an already shaped profile. Such profile can for examplebe generated by interference of two laser beams.

In a preferred embodiment of the present invention, the display issubjected to a second UV irradiation step, preferably without aphotomask applied, after the first UV irradiation step as describedabove. Thereby it is possible to complete polymerisation of monomersthat were not or only partially polymerised in the first step. Thesecond UV step can have an emission spectrum and/or intensity which isthe same as that of the first step, or which is different from the firststep.

Alternatively two applying two separate irradiation steps, the intensityis changed during UV exposure. Preferably, the intensity is graduallyincreased during UV exposure.

For example, an LC display according to the present invention can bemanufactured as follows. Polymerisable compounds as described above andbelow are combined with a suitable LC host mixture. This resulting LCmedium can then be included into the display by using conventionalmanufacturing processes. The resulting LC medium can be filled forexample using capillary forces into the cell gap formed by twosubstrates.

Alternatively, the LC medium can be deposited as a layer onto asubstrate, and another substrate is placed on top of the LC layer undervacuum in order to prevent inclusion of air bubbles. The LC medium is ineither case located in the cell gap formed by the two substrates, asexemplarily illustrated in FIG. 1a . These substrates usually arecovered by an alignment layer which is in direct contact with the LCmedium. The substrates itself can carry other functional components likeTFTs, black matrix, colour filter, or similar.

Subsequently, polymerization induced phase separation is initiated byexposure of the LC medium, which is either in the nematic or theisotropic phase, to UV radiation with collimated light through aphotomask, as exemplarily illustrated in FIG. 1b . This leads to theformation of polymer wall structures, restoration of the LC host, andalignment of the LC phase with the alignment layer, as exemplarilyillustrated in FIG. 1 c.

This process can advantageously utilize display manufacturing processesthat are established in the industry. Thus, both the display fillingprocess, for example by one-drop-filling (ODF), and the radiationinitiated polymerization step after sealing the display, which is knownfor example from polymer stabilised or PS-type display modes like PS-VA,are established techniques in conventional LCD manufacturing.

A preferred LC display of the present invention comprises:

-   -   a first substrate including a pixel electrode defining pixel        areas, the pixel electrode being connected to a switching        element disposed in each pixel area and optionally including a        micro-slit pattern, and optionally a first alignment layer        disposed on the pixel electrode,    -   a second substrate including a common electrode layer, which may        be disposed on the entire portion of the second substrate facing        the first substrate, and optionally a second alignment layer,    -   an LC layer disposed between the first and second substrates and        including an LC medium comprising a polymerisable component A)        and a liquid-crystalline component B) as described above and        below, wherein the polymerisable component A) is polymerised.

The LC display may comprise further elements, like a colour filter, ablack matrix, a passivation layer, optical retardation layers,transistor elements for addressing the individual pixels, etc., all ofwhich are well known to the person skilled in the art and can beemployed without inventive skill.

The electrode structure can be designed by the skilled person dependingon the individual display type. For example for VA displays amulti-domain orientation of the LC molecules can be induced by providingelectrodes having slits and/or bumps or protrusions in order to createtwo, four or more different tilt alignment directions.

The first and/or second alignment layer controls the alignment directionof the LC molecules of the LC layer. For example, in TN displays thealignment layer is selected such that it imparts to the LC molecules anorientation direction parallel to the surface, while in VA displays thealignment layer is selected such that it imparts to the LC molecules ahomeotropic alignment, i.e. an orientation direction perpendicular tothe surface. Such an alignment layer may for example comprise apolyimide, which may also be rubbed, or may be prepared by aphotoalignment method.

The substrate can be a glass substrate, for example in case of a curveddisplay. The use of an LC medium according to the present invention inan LC display with glass substrates can provide several advantages. Forexample, the formation of polymer wall structures in the LC medium helpsto prevent the so-called “pooling effect” where pressure applied on theglass substrates causes unwanted optical defects. The stabilizing effectof the polymer wall structures also allows to further minimize the panelthickness. Moreover, in bent panels with glass substrates the polymerwall structures enable a smaller radius of curvature.

For flexible LC displays preferably plastic substrates are used. Theseplastic substrates preferably have a low birefringence. Examples arepolycarbonate (PC), polyethersulfone (PES), polycyclic olefine (PCO),polyarylate (PAR), polyetheretherketone (PEEK), or colourless polyimide(CPI) substrates.

The LC layer with the LC medium can be deposited between the substratesof the display by methods that are conventionally used by displaymanufacturers, for example the one-drop-filling (ODF) method. Thepolymerisable component of the LC medium is then polymerised for exampleby UV photopolymerisation.

In case the polymerisable compounds are used as a replacement for spacerparticles, the display manufacturing process preferably comprises thefollowing steps:

In a first step, the LC medium containing the LC host and monomerprecursor is applied to one of the two substrates, preferably by usingone of the following deposition methods: one drop filling, ink jetprinting, spin coating, slit coating, flexo printing, or a comparablemethod. The substrate in that instance may carry a colour filter, TFTdevices, a black matrix, a polyimide coating, or other componentstypically found on a display substrate. The applied LC medium forms athin, uniform film with the thickness of the targeted cell gap of thefinal device.

In a second step, the applied film is subjected to UV radiation havingan intensity profile. This profile is generated for example byirradiating through a photomask, using laser interference, direct laserwriting, or a comparable method. Irradiation of the film can eitheroccur from either side of the substrate. In case of using a photomask,the mask can either placed on the substrate and the LC film is cured bythe light passing through the substrate, or the mask is directly broughtin close proximity to the LC film and the LC medium is cured directly.

In this second step, polymer wall structures are created that functionas spacer.

Subsequently, the second substrate, which may also carry colour filter,TFT devices, a black matrix, a polyimide coating, or other componentstypically found on a display substrate, is place on top of the firstsubstrate so that the LC film comes to rest in between the twosubstrates.

A further irradiation is now optionally possible to convert unreactedmonomers, generate adhesion between the two substrates, and/or seal theedges of the display.

The polymerisation of the polymerisable compounds can be carried out inone step or in two or more steps. It is also possible to carry out thepolymerisation in a sequence of several UV irradiation and/or heating orcooling steps. For example, a display manufacturing process may includea first UV irradiation step at room temperature to produce a pretiltangle, and subsequently, in a second polymerisation step to polymeriseor crosslink the compounds which have not reacted in the first step(“end curing”).

Upon polymerisation the polymerisable compounds react with each other toa polymer which undergoes macroscopical phase-separation from the LChost mixture and forms polymer walls in the LC medium.

Suitable and preferred polymerisation methods are, for example, thermalor photopolymerisation, preferably photopolymerisation, in particular UVinduced photopolymerisation, which can be achieved by exposure of thepolymerisable compounds to UV radiation.

Optionally one or more polymerisation initiators are added to the LCmedium. Suitable conditions for the polymerisation and suitable typesand amounts of initiators are known to the person skilled in the art andare described in the literature. Suitable for free-radicalpolymerisation are, for example, the commercially availablephotoinitiators Irgacure651®, Irgacure184®, Irgacure907®, Irgacure369®or Darocure1173® (Ciba AG). If a polymerisation initiator is employed,its proportion is preferably 0.001 to 5% by weight, particularlypreferably 0.001 to 1% by weight.

The polymerisable compounds according to the invention are also suitablefor polymerisation without an initiator, which is accompanied byconsiderable advantages, such, for example, lower material costs and inparticular less contamination of the LC medium by possible residualamounts of the initiator or degradation products thereof. Thepolymerisation can thus also be carried out without the addition of aninitiator. In a preferred embodiment, the LC medium contains apolymerisation initiator.

The LC medium may also comprise one or more stabilisers or inhibitors inorder to prevent undesired spontaneous polymerisation of the RMs, forexample during storage or transport. Suitable types and amounts ofstabilisers are known to the person skilled in the art and are describedin the literature. Particularly suitable are, for example, thecommercially available stabilisers from the Irganox® series (Ciba AG),such as, for example, Irganox® 1076. If stabilisers are employed, theirproportion, based on the total amount of RMs or the polymerisablecomponent (component A), is preferably 10-500,000 ppm, particularlypreferably 50-50,000 ppm.

Preferably the LC medium according to the present invention doesessentially consist of a polymerisable component A) and an LC componentB) (or LC host mixture) as described above and below. However, the LCmedium may additionally comprise one or more further components oradditives.

The LC media according to the invention may also comprise furtheradditives which are known to the person skilled in the art and aredescribed in the literature, such as, for example, polymerisationinitiators, inhibitors, stabilisers, surface-active substances or chiraldopants. These may be polymerisable or non-polymerisable. Polymerisableadditives are accordingly ascribed to the polymerisable component orcomponent A). Non-polymerisable additives are accordingly ascribed tothe non-polymerisable component or component B).

Preferred additives are selected from the list including but not limitedto co-monomers, chiral dopants, polymerisation initiators, inhibitors,stabilizers, surfactants, wetting agents, lubricating agents, dispersingagents, hydrophobing agents, adhesive agents, flow improvers, defoamingagents, deaerators, diluents, reactive diluents, auxiliaries,colourants, dyes, pigments and nanoparticles.

In a preferred embodiment the LC media contain one or more chiraldopants, preferably in a concentration from 0.01 to 1% by weight, verypreferably from 0.05 to 0.5% by weight. The chiral dopants arepreferably selected from the group consisting of compounds from Table Bbelow, very preferably from the group consisting of R- or S-1011, R- orS-2011, R- or S-3011, R- or S-4011, and R- or S-5011.

In another preferred embodiment the LC media contain a racemate of oneor more chiral dopants, which are preferably selected from the chiraldopants mentioned in the previous paragraph.

Furthermore, it is possible to add to the LC media, for example, 0 to15% by weight of pleochroic dyes, furthermore nanoparticles, conductivesalts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate,tetrabutyl-ammonium tetraphenylborate or complex salts of crown ethers(cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258(1973)), for improving the conductivity, or substances for modifying thedielectric anisotropy, the viscosity and/or the alignment of the nematicphases. Substances of this type are described, for example, in DE-A 2209 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53728.

The LC media which can be used in accordance with the invention areprepared in a manner conventional per se, for example by mixing one ormore of the above-mentioned compounds with one or more polymerisablecompounds as defined above, and optionally with furtherliquid-crystalline compounds and/or additives. In general, the desiredamount of the components used in lesser amount is dissolved in thecomponents making up the principal constituent, advantageously atelevated temperature. It is also possible to mix solutions of thecomponents in an organic solvent, for example in acetone, chloroform ormethanol, and to remove the solvent again, for example by distillation,after thorough mixing. The invention furthermore relates to the processfor the preparation of the LC media according to the invention.

It goes without saying to the person skilled in the art that the LCmedia according to the invention may also comprise compounds in which,for example, H, N, O, Cl, F have been replaced by the correspondingisotopes like deuterium etc.

The following examples explain the present invention without restrictingit. However, they show the person skilled in the art preferred mixtureconcepts with compounds preferably to be employed and the respectiveconcentrations thereof and combinations thereof with one another. Inaddition, the examples illustrate which properties and propertycombinations are accessible.

Throughout the patent application and in the working examples, thestructures of the liquid-crystal compounds are indicated by means ofacronyms. Unless indicated otherwise, the transformation into chemicalformulae takes place in accordance with Tables I-III. All radicalsC_(n)H_(2n+1), C_(m)H_(2m+1), C_(n)H_(2n), C_(m)H_(2m) and C_(k)H_(2k)are straight-chain alkyl radicals or alkenyl radicals respectively, ineach case having n, m or k C atoms; n and m each, independently of oneanother, denote 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 1,2, 3, 4, 5 or 6, and k is 0, 1, 2, 3, 4, 5 or 6. In Table I the ringelements of the respective compound are coded, in Table II the bridgingmembers are listed and in Table III the meanings of the symbols for theleft-hand and right-hand side chains of the compounds are indicated.

TABLE I Ring elements

TABLE II Bridging members E —CH₂CH₂— V —CH═CH— T —C≡C— W —CF₂CF₂— Z—COO— ZI —OCO— O —CH₂O— OI —OCH₂— Q —CF₂O— QI —OCF₂—

TABLE III Side chains Left-hand side chain Right-hand side chain n-C_(n)H_(2n+1)— -n —C_(n)H_(2n+1) nO- C_(n)H_(2n+1)—O— -On—O—C_(n)H_(2n+1) V— CH₂═CH— —V —CH═CH₂ nV- C_(n)H_(2n+1)—CH═CH— -nV—C_(n)H_(2n)—CH═CH₂ Vn- CH₂═CH—C_(n)H_(2n)— -Vn —CH═CH—C_(n)H_(2n+1)nVm- C_(n)H_(2n+1)—CH═CH—C_(m)H_(2m)— -nVm—C_(n)H_(2n)—CH═CH—C_(m)H_(2m+1) N— N≡C— —N —C≡N F— F— —F —F Cl— Cl— —Cl—Cl M- CFH₂— -M —CFH₂ D- CF₂H— -D —CF₂H T- CF₃— -T —CF₃ MO- CFH₂O— -OM—OCFH₂ DO- CF₂HO— -OD —OCF₂H TO- CF₃O— -OT —OCF₃ T- CF₃— -T —CF₃ A-H—C≡C— -A —C≡C—H FXO- CF₂═CHO— -OXF —OCH═CF₂

Preferred mixture components are shown in Tables A1 and A2 below. Thecompounds shown in Table A1 are especially suitable for use in LCmixtures with positive dielectric anisotropy. The compounds shown inTable A2 are especially suitable for use in LC mixtures with negativedielectric anisotropy.

TABLE Al In Table Al, R^(1*) denotes a group selected from the left-handside chains and R^(2*) denotes a group selected from the right-hand sidechains listed in Table III, L^(1*) and L^(2*) are independently of eachother H or F, m and n are independently of each other an integer from 1to 12, preferably 1, 2, 3, 4, or 6, k is 0, 1, 2, 3, 4, 5 or 6, and(O)C_(m)H_(2m+1) means C_(m)H_(2m+1) or OC_(m)H_(2m+1).

TABLE A2 In the formulae below m and n are independently of each otheran integer from 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3,4, 5 or 6 and (O)C_(m)H_(2m+1) means C_(m)H_(2m+1) or OC_(m)H_(2m+1).

In a first preferred embodiment of the present invention, the LC mediaaccording to the invention, especially those with positive dielectricanisotropy, comprise one or more compounds selected from the groupconsisting of compounds from Table A1.

In a second preferred embodiment of the present invention, the LC mediaaccording to the invention, especially those with negative dielectricanisotropy, comprise one or more compounds selected from the groupconsisting of compounds from Table A2.

TABLE B Table B shows possible chiral dopants which can be added to theLC media according to the invention.

C 15

CB 15

CM 21

R/S-811

CM 44

CM 45

CM 47

CN

R/S-2011

R/S-3011

R/S-4011

R/S-5011

R/S-1011

The LC media preferably comprise 0 to 10% by weight, in particular 0.01to 5% by weight, particularly preferably 0.1 to 3% by weight, ofdopants. The LC media preferably comprise one or more dopants selectedfrom the group consisting of compounds from Table B.

TABLE C Table C shows possible stabilisers which can be added to the LCmedia according to the invention. Therein n denotes an integer from 1 to12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups arenot shown.

The LC media preferably comprise 0 to 10% by weight, in particular 1 ppmto 5% by weight, particularly preferably 1 ppm to 1% by weight, ofstabilisers.

The LC media preferably comprise one or more stabilisers selected fromthe group consisting of compounds from Table C.

In addition, the following abbreviations and symbols are used:

-   V₀ threshold voltage, capacitive [V] at 20° C.,-   n_(e) extraordinary refractive index at 20° C. and 589 nm,-   n_(o) ordinary refractive index at 20° C. and 589 nm,-   Δn optical anisotropy at 20° C. and 589 nm,-   ε_(⊥) dielectric permittivity perpendicular to the director at    20° C. and 1 kHz,-   ε_(∥) dielectric permittivity parallel to the director at 20° C. and    1 kHz,-   Δε dielectric anisotropy at 20° C. and 1 kHz,-   cl.p., T(N,I) clearing point [° C.],-   γ₁ rotational viscosity at 20° C. [mPa·s],-   K₁ elastic constant, “splay” deformation at 20° C. [pN],-   K₂ elastic constant, “twist” deformation at 20° C. [pN],-   K₃ elastic constant, “bend” deformation at 20° C. [pN].

Unless explicitly noted otherwise, all concentrations and ratios in thepresent application are quoted in percent by weight, and preferablyrelate to the corresponding mixture as a whole, comprising all solid orliquid-crystalline components, without solvents.

Unless explicitly noted otherwise, all temperature values indicated inthe present application, such as, for example, for the melting pointT(C,N), the transition from the smectic (S) to the nematic (N) phaseT(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (°C.). M.p. denotes melting point, cl.p.=clearing point. Furthermore,C=crystalline state, N=nematic phase, S=smectic phase and I=isotropicphase. The data between these symbols represent the transitiontemperatures.

All physical properties are and have been determined in accordance with“Merck Liquid Crystals, Physical Properties of Liquid Crystals”, StatusNovember 1997, Merck KGaA, Germany, and apply for a temperature of 20°C., and Δn is determined at 589 nm and Δε at 1 kHz, unless explicitlyindicated otherwise in each case.

The term “threshold voltage” for the present invention relates to thecapacitive threshold (V₀), also known as the Freedericks threshold,unless explicitly indicated otherwise. In the examples, the opticalthreshold may also, as generally usual, be quoted for 10% relativecontrast (V₁₀).

Example 1

The nematic LC host mixture N1 is formulated as follows.

APUQU-2-F 6.00% cl.p. 79.5° C. APUQU-3-F 6.00% Δn 0.1086 CC-3-V 44.50%Δε 9.6 CC-3-V1 4.00% ε_(∥) 12.9 CCP-30CF3 7.00% γ₁ 67 mPa · s CCP-V-15.00% CPGU-3-OT 3.00% PGP-2-V 5.50% PGUQU-3-F 3.00% PGUQU-4-F 7.00%PGUQU-5-F 3.00% PUQU-3-F 6.00%

Example 2

The nematic LC host mixture N2 is formulated as follows.

PUQU-3-F 5.50 cl.p. 80.1° C. CC-3-V 40.00 Δn 0.1095 CC-3-V1 10.00 Δε 9.1CCP-V1 10.00 ε_(∥) 12.4 APUQU-2-F 5.00 γ₁ 65 mPa · s APUQU-3-F 10.50PGUQU-3-F 3.50 PGUQU-4-F 8.00 PGP-2-2V 7.50

Example 3

The nematic LC host mixture N3 is formulated as follows.

CC-3-V 40.00 cl.p. 81.5° C. CC-3-V1 8.00 Δn 0.0827 PUQU-2-F 3.00 Δε 9.4PUQU-3-F 8.00 ε_(∥) 12.8 APUQU-2-F 7.00 γ₁ 75 mPa · s APUQU-3-F 7.00CCP-3-1 7.00 CCOC-3-3 5.00 CCOC-4-3 5.00 CDUQU-3-F 10.00

Polymerisable Mixture Examples Polymerisable Mixture Preparation:

Polymerisable LC media for polymer wall formation are prepared by mixingLC host, monomer and photoinitiator and then homogenizing the resultingmixture by heating above the clearing point.

The structures of the monomer (including its formula and name in thecomposition table) are listed below.

The mixture compositions are shown in Table 1 below.

TABLE 1 Polymerisable Mixture Compositions [Monomer [Monomer [MonomerIRG- [Host] 1] 2] Monomer 3/4] 651 No. Host (%) Monomer 1 (%) Monomer 2(%) 3/4 (%) [%] 1 N1 87.88 I2a 3.60 II1a1 8.00 III4b1 0.20 0.12 III1a20.20 2 N1 87.88 I2a 8.00 II1a1 3.60 III4b1 0.20 0.12 III1a2 0.20 3 N187.88 I2a 1.60 II1a1 10.00 III4b1 0.20 0.12 III1a2 0.20 4 N1 87.88 I2a1.60 II1a14 10.00 III4b1 0.20 0.12 III1a2 0.20 5 N1 87.88 I2a 3.60II1a14 8.00 III4b1 0.20 0.12 III1a2 0.20 6 N1 87.88 I2a 8.00 II1a14 3.60III4b1 0.20 0.12 III1a2 0.20 7 N1 87.88 I2b 3.60 II1a13 8.00 III4b1 0.200.12 III1a2 0.20 8 N1 87.88 I2a 3.60 II1a13 8.00 III4b1 0.20 0.12 III1a20.20 9 N2 86.87 I3a 6.00 II1a7 6.00 III4b1 1.00 0.13 10 N2 86.87 I3a6.00 II1a1 6.00 III4b1 1.00 0.13 11 N2 86.87 I3a 6.00 II1a1 6.00 III1a11.00 0.13 12 N2 86.87 I3a 6.00 II1a1 6.00 III1a2 1.00 0.13 13 N3 86.87I3a 6.00 II1a7 6.00 III1a1 1.00 0.13 14 N3 84.85 I2a 15.00 — — — — 0.1515 N3 84.85 I2a 14.00 — — III1a8 1.00 0.15 16 N2 86.87 I3a 6.00 IIA1a16.00 III1a20 1.00 0.13 17 N2 86.87 I3a 6.00 IIA1a1 6.00 III1a1 1.00 0.13

Polymerisable mixtures 1-17 according to the invention contain hostmixture N1, N2 or N3 having positive dielectric anisotropy, and furthercontain a monoreactive first monomer of formula I, optionally amonoreactive second monomer of formula II or IIA, and optionally one ortwo di- or multireactive third monomers of formula III, respectively.

Test Cells:

The test cells comprise two glass substrates coated with ITO, which arekept apart by spacer particles or foils at a layer thickness of 3-4microns and glued together by an adhesive (usually Norland, NEA 123). Ontop of the electrode layers polyimide alignment layers (Nissan SE-6514or SE2414) are applied which are rubbed parallel or antiparallel.

Wall Formation:

The test cells are filled with the LC medium and placed on a black,non-reflecting surface. A photomask is placed on top of the test cellsand the sample is subjected for 30 min to UV radiation (Hg/Xe arch lamp,LOT QuantumDesign Europe, LS0205, intensity at sample 4 mW/cm² measuredat 365+/−10 nm FWHM). Radiation of the emission spectrum below 320 nm isremoved by a dichroic mirror. The photomask usually has a pattern ofequidistant lines of the same thickness. Typical line thickness is 10microns, typical distance between the lines is 100 microns.

Characterization:

Samples are analyzed under a polarization microscope. The isotropicpolymer walls can clearly be distinguished from areas containingbirefringend LC. The width of the walls and inclusions of LC into thepolymer walls, and defects in the pixel area caused by contamination ofpolymer, or misalignment of the LC caused by the wall formation processcan be observed.

Mechanical Stress Test:

Test cells are subjected to a mechanical stress by applying pressure tothe top substrate by a 0.5 mm² tip with a force of 10N for 10 s. Damagesto the polymer wall structure are evaluated with the polarizationmicroscope.

It was observed that the polymer wall structure did not show significantdamages caused by mechanical stress.

Electron Micrographs:

The structure of the polymer walls and contamination of the pixel areaby polymer are investigated by taking electron micrographs. The samplesare prepared by either lifting off the top substrate for top-viewimages, or breaking the glass slides in half for viewing the crosssection of the walls. The LC is removed by flushing the sample withethanol, subsequently the substrates is dried in an air flow and sputtercoated with a conductive layer (gold).

Electro-Optical Characterization:

The electro-optical properties of the liquid crystal host arecharacterized by applying an electrical potential between 0 and 10V insteps of 0.05V. The resulting response is recorded by measuring thetransmission change of the sample in between crossed polarizers (DMS 301equipped with integration sphere).

It was observed that the electrooptical properties of the liquid crystalhost were not significantly affected by the polymer wall structures.

Device Examples

Polymerisable LC mixtures 1-17 are each filled into a test cell andsubjected to UV irradiation under a photomask as described above. FIG.2-10 show polarization microscope images of the test cells prepared frompolymerisable mixtures 1-8, respectively, after polymerization. Theformed polymer walls can be seen as dark lines.

FIG. 10-18 show polarization microscope images of test cells preparedfrom polymerisable mixtures 9-17, respectively, after polymerization(a), after mechanical stress test (b) and after thermal stress test (c).The formed polymer walls can be seen as dark lines.

1. A liquid crystal (LC) medium comprising a polymerisable component A)which comprises one or more polymerisable compounds, and aliquid-crystalline component B) which comprises one or more mesogenic orliquid-crystalline compounds, characterized in that polymerisablecomponent A) comprises one or more first polymerisable compoundscomprising a monocyclic hydrocarbon group having from 8 to 24 ringatoms, and attached thereto one polymerisable group.
 2. The LC medium ofclaim 1, characterized in that component A) additionally comprises oneor more second polymerisable compounds comprising a straight-chain orbranched hydrocarbon group having from 1 to 30 C atoms, or a monocyclichydrocarbon group having from 3 to 7 ring atoms, or a bi- or polycyclichydrocarbon group having from 4 to 30 ring atoms, and attached theretoone polymerisable group.
 3. The LC medium of claim 1, characterized inthat component A) additionally comprises one or more third polymerisablecompounds comprising a straight-chain, branched or cyclic hydrocarbongroup having from 1 to 30 C atoms and attached thereto two or morepolymerisable groups.
 4. The LC medium according to claim 1,characterized in that component A) comprises one or more firstpolymerisable compounds selected from formula IP-Sp-G¹  I wherein P is a polymerisable group, Sp is a spacer group or asingle bond, G¹ is a monocyclic hydrocarbon group having 8 to 24 Catoms, which is optionally substituted by one or more groups L, L is F,Cl, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R^(x))₂, —C(═O)Y¹,—C(═O)R^(x), —N(R^(x))₂, optionally substituted silyl, optionallysubstituted aryl or heteroaryl having 5 to 20 ring atoms, orstraight-chain or branched alkyl having 1 to 25 C atoms in which, inaddition, one or more non-adjacent CH₂ groups may each be replaced,independently of one another, by —C(R⁰)═C(R⁰⁰)—, —C≡C—, —N(R⁰)—, —O—,—S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atomsare not linked directly to one another, and in which, in addition, oneor more H atoms may be replaced by F, Cl, —CN, R^(x) is H, F, Cl, CN, orstraight chain, branched or cyclic alkyl having 1 to 25 C atoms, whereinone or more non-adjacent CH₂-groups are optionally replaced by —O—, —S—,—CO—, —CO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/or S-atomsare not directly connected with each other, and wherein one or more Hatoms are each optionally replaced by F or Cl, R⁰, R⁰⁰ are H or alkylhaving 1 to 20 C atoms, Y¹ is halogen.
 5. The LC medium according toclaim 4, characterized in that component A) comprises one or more firstpolymerisable compounds selected from the following formulae

wherein P and Sp have the meanings given in claim
 4. 6. The LC mediumaccording to claim 1, characterized in that component A) comprises oneor more first polymerisable compounds selected from the followingformulae


7. The LC medium according to claim 4, characterized in that componentA) comprises one or more second polymerisable compounds selected fromformula IIP-Sp-G²  II wherein P and Sp have the meanings given in claim 4, and G²is a straight-chain or branched alkyl group with 1 to 20 C atoms, or amonocyclic alkyl group with 3 to 7 C atoms, that is optionally mono-,poly- or perfluorinated and is optionally substituted by one or moregroups L as defined in claim 4, and wherein one or more CH₂-groups areoptionally replaced by —O—, —CO—, —O—CO— or —CO—O— such that O-atoms arenot directly adjacent to one another.
 8. The LC medium according toclaim 4, characterized in that component A) comprises one or more secondpolymerisable compounds selected from the following formulaeP-Sp-(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)—CH₃  II1P-Sp-(CH₂)_(n2)—(CF₂)_(n1)—CFW¹³W¹⁴  II2

wherein the individual radicals, independently of each other and on eachoccurrence identically or differently, have the following meanings P, Sphave the meanings given in claim 4, W¹¹, W¹² are H, F or straight-chainor branched C₁-C₁₂-alkyl, W¹³, W¹⁴ are H or F, n1 is an integer from 2to 15, n2, n3 are 0 or an integer from 1 to 3,
 9. The LC mediumaccording to claim 1, characterized in that component A) comprises oneor more second polymerisable compounds selected from the followingformulae


10. The LC medium according to claim 1, characterized in that componentA) comprises one or more second polymerisable compounds comprising a bi-or polycyclic hydrocarbon group having from 4 to 30 ring atoms, andattached thereto a polymerisable group.
 11. The LC medium according toclaim 1, characterized in that component A) comprises one or more secondpolymerisable compounds selected from formula IIAP-Sp-G^(2A)  IIA wherein P is a polymerisable group, Sp is a spacergroup or a single bond, G^(2A) is a bi- or polycyclic hydrocarbon grouphaving 4 to 30 ring atoms, which is optionally substituted by one ormore groups L, and L is F, Cl, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN,—C(═O)N(R^(x))₂, —C(═O)Y¹, —C(═O)R^(x), —N(R^(x))₂, optionallysubstituted silyl, optionally substituted aryl or heteroaryl having 5 to20 ring atoms, or straight-chain or branched alkyl having 1 to 25 Catoms in which, in addition, one or more non-adjacent CH₂ groups mayeach be replaced, independently of one another, by —C(R⁰)═C(R⁰⁰)—,—C≡C—, —N(R⁰)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a waythat O and/or S atoms are not linked directly to one another, and inwhich, in addition, one or more H atoms may be replaced by F, Cl, —CN.12. The LC medium according to claim 4, characterized in that componentA) comprises one or more second polymerisable compounds selected fromthe following formulae

wherein R on each occurrence identically or differently denotes P-Sp- orhas one of the meanings given for R^(x) in claim 4, and at least one ofthe groups R in each of formulae IIAA-IIAC denotes P-Sp-.
 13. The LCmedium according to claim 4, characterized in that component A)comprises one or more second polymerisable compounds selected from thefollowing formulae

wherein P and Sp have the meanings given in claim 4, W¹¹, W¹² and W¹³are independently of each other H, F or C₁-C₁₂-alkyl, and the cycloalkylgroups are optionally substituted with one or more groups L as definedin claim
 4. 14. The LC medium according to claim 1, characterized inthat component A) comprises one or more second polymerisable compoundsselected from the following formulae

wherein n is 0 or an integer from 1 to 8, W is H, CH₃ or C₂H₅ and W¹¹,W¹² and W¹³ are H, F or C₁-C₁₂-alkyl.
 15. The LC medium according toclaim 1, characterized in that component A) comprises one or more secondpolymerisable compounds selected from the following formulae


16. The LC medium according to claim 4, characterized in that componentA) comprises one or more third polymerisable compounds selected offormula IIIP¹-Sp¹-G³-Sp²-P²  III wherein P¹ and P² independently of each other andon each occurrence identically or differently denote a polymerisablegroup, Sp¹, Sp² denote independently of each other identical ordifferent spacer groups or a single bond, G³ is a straight-chain,branched or cyclic alkyl group with 1 to 20 C atoms that is optionallymono-, poly- or perfluorinated and is optionally substituted by one ormore groups L as defined in claim 4, and wherein one or more CH₂-groupsare optionally replaced by —O—, —CO—, —O—CO— or —CO—O— such that O-atomsare not directly adjacent to one another.
 17. The LC medium according toclaim 16, characterized in that component A) comprises one or more thirdpolymerisable compounds selected from the following formulaeP¹-Sp¹-(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)-Sp²-P²  III1

P¹—(CH₂)_(n2)—(CF₂)_(n1)—(CH₂)_(n3)—P²  III3(P¹-Sp¹-(CH₂)_(n4))_(n5)CH_(4-n5)  III4 wherein P¹, P², Sp¹, Sp² are asdefined in claim 16, W¹¹ is, on each occurrence identically ordifferently, H, F or C₁-C₁₂-alkyl, n1 is an integer from 2 to 15, n2, n3are independently of each other 0 or an integer from 1 to 3, n4 is 0 oran integer from 1 to 15, n5 is 3 or 4, and the cyclohexylene ring informula III2 is optionally substituted by one or more identical ordifferent groups W¹¹.
 18. The LC medium according to claim 17,characterized in that component A) comprises one or more thirdpolymerisable compounds selected from the following formulaeCH₂═CW—CO—O—(CHW¹¹)_(n4)—(CH₂)_(n1)—O—CH═CH₂  III1aCH₂═CH—O—(CHW¹)_(n4)—(CH₂)_(n1)—O—CO—CH═CH₂  III1bCH₂═CW—CO—O—(CHW¹¹)_(n2)—(CH₂)_(n1)—(CHW¹²)_(n3)—O—CO—CW═CH₂  III1c

CH₂═CW—CO—O—(CH₂)_(n2)—(CF₂)_(n1)—(CH₂)_(n3)—O—CH═CH₂  III3aCH₂═CW—CO—O—(CH₂)_(n2)—(CF₂)_(n1)—(CH₂)_(n3)—O—CO—CW═CH₂  III3b(CH₂═CW—CO—O—(CH₂)_(n2))₃CH  III4a(CH₂═CW—CO—O—(CH₂)_(n2))₄C  III4b wherein W is H, CH₃ or C₂H₅ and W¹¹,n1, n2 and n4 are as defined in claim 17, and the cyclohexylene ring informula III2a-c is optionally substituted by one or more identical ordifferent groups W¹¹.
 19. The LC medium according to claim 1,characterized in that component A) comprises one or more thirdpolymerisable compounds selected from the following formulae


20. The LC medium according to claim 1, characterized in that componentA) comprises one or more fourth polymerisable compounds comprising aring system containing one or more aromatic or heteroaromatic rings orcondensed aromatic or heteroaromatic rings, and attached thereto twopolymerisable groups that are different from each other.
 21. The LCmedium according to claim 1, characterized in that component A)comprises one or more fourth polymerisable compounds selected from thefollowing formulaP¹—Sp¹-B¹—(Z^(b)—B²)_(m)-Sp²-P²  IV P¹ and P² independently of eachother and on each occurrence identically or differently denote apolymerisable group, Sp¹, Sp² denote independently of each otheridentical or different spacer groups or a single bond, B¹ and B² areindependently of each other, and on each occurrence identically ordifferently, an aromatic, heteroaromatic, alicyclic or heterocyclicgroup having 4 to 25 ring atoms, which may also contain fused rings, andwhich is unsubstituted, or mono- or polysubstituted by L as defined inclaim 4, wherein at least one of B¹ and B² denotes an aromatic orheteroaromatic group, L is F, Cl, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN,—C(═O)N(R^(x))₂, —C(═O)Y¹, —C(═O)R^(x), —N(R^(x))₂, optionallysubstituted silyl, optionally substituted aryl or heteroaryl having 5 to20 ring atoms, or straight-chain or branched alkyl having 1 to 25 Catoms in which, in addition, one or more non-adjacent CH₂ groups mayeach be replaced, independently of one another, by —C(R⁰)═C(R⁰⁰)—,—C≡C—, —N(R⁰)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a waythat O and/or S atoms are not linked directly to one another, and inwhich, in addition, one or more H atoms may be replaced by F, Cl, —CNZ^(b) is, on each occurrence identically or differently, —O—, —S—, —CO—,—CO—O—, —OCO—, —O—CO—O—, —OCH₂—, —CH₂O—, —SCH₂—, —CH₂S—, —CF₂O—, —OCF₂—,—CF₂S—, —SCF₂—, —(CH₂)_(n1)—, —CF₂CH₂—, —CH₂CF₂—, —(CF₂)_(n11)—,—CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR⁰R⁰⁰ or a singlebond, R⁰ and R⁰⁰ each, independently of one another, denote H or alkylhaving 1 to 12 C atoms, m denotes 0, 1, 2, 3 or 4, n11 denotes 1, 2, 3or
 4. 22. The LC medium according to claim 16, characterized in thatcomponent A) comprises one or more fourth polymerisable compoundsselected from the following formulae

in which P¹, P², Sp¹, Sp² and L are as defined in claim 16, Z¹ is —O—,—CO—, —C(R^(y)R^(z))— or —CF₂CF₂—, Z², Z³ are independently of eachother —CO—O—, —O—CO—, —CH₂O—, —OCF₂— or —(CH₂)_(n11)—, where n11 is 2, 3or 4, r is 0, 1, 2, 3 or 4, s is 0, 1, 2 or 3, t is 0, 1 or
 2. 23. TheLC medium according to claim 1, characterized in that the totalconcentration of the first, second, third and fourth polymerisablecompounds in the LC medium is from 1 to 30% by weight.
 24. The LC mediumaccording to claim 1, characterized in that the ratio of firstpolymerisable compounds relative to the second polymerisable compoundsin the LC medium is from 10:1 to 1:10.
 25. The LC medium according toclaim 1, characterized in that component B) comprises one or morecompounds selected from formulae A and B

in which the individual radicals have, independently of each other andon each occurrence identically or differently, the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

R²¹, R³¹ each, independently of one another, alkyl, alkoxy, oxaalkyl oralkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9C atoms, all of which are optionally fluorinated, X⁰ F, Cl, halogenatedalkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl oralkenyloxy having 2 to 6 C atoms, Z³¹ —CH₂CH₂—, —CF₂CF₂—, —COO—,trans-CH═CH—, trans-CF═CF—, —CH₂O— or a single bond, L²¹, L²², L³¹, L³²,each, independently of one another, H or F, g 0, 1, 2 or
 3. 26. The LCmedium according to claim 25, characterized in that component B)comprises, in addition to the compounds of formula A and/or B, one ormore compounds of formula E containing an alkenyl group

in which the individual radicals, on each occurrence identically ordifferently, each, independently of one another, have the followingmeaning:

R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the rings X,Y and Z denotes cyclohexenyl, also one of the meanings of R^(A2), R^(A2)alkyl having 1 to 12 C atoms, in which, in addition, one or twonon-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or—COO— in such a way that O atoms are not linked directly to one another,x 1 or
 2. 27. The LC medium according to claim 1, characterized in thatcomponent B) comprises one or more compounds selected from formulae CYand PY:

wherein a denotes 1 or 2, b denotes 0 or 1,

R¹ and R² each, independently of one another, denote alkyl having 1 to12 C atoms, where, in addition, one or two non-adjacent CH₂ groups maybe replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that Oatoms are not linked directly to one another, Z^(x) and Z^(y) each,independently of one another, denote —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—,—CH₂O—, —OCH₂—, —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or asingle bond, L¹⁻⁴ each, independently of one another, denote F, Cl,OCF₃, CF₃, CH₃, CH₂F, CHF₂.
 28. The LC medium according to claim 27,characterized in that component B) comprises one or more alkenylcompounds selected from formulae AN and AY

in which the individual radicals, on each occurrence identically ordifferently, and each, independently of one another, have the followingmeaning:

R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the rings X,Y and Z denotes cyclohexenyl, also one of the meanings of R^(A2), R^(A2)alkyl having 1 to 12 C atoms, in which, in addition, one or twonon-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or—COO— in such a way that O atoms are not linked directly to one another,Z^(x) —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—,—C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond, L^(1,2) H, F, Cl, OCF₃,CF₃, CH₃, CH₂F or CHF₂H, x 1 or 2, z 0 or
 1. 29. The LC medium accordingto claim 1 characterized in that the polymerisable compounds arepolymerised.
 30. An LC display comprising an LC medium according toclaim
 1. 31. The LC display of claim 30, which is a flexible or curveddisplay.
 32. The LC display of claim 30, which is a TN, OCB, IPS, FFS,posi-VA, VA or UB-FFS display.
 33. A process for the production of an LCdisplay, comprising providing an LC medium as defined in claim 1 intothe display, and polymerising the polymerisable compounds in definedregions of the display.
 34. The process of claim 33, wherein thepolymerisable compounds are photopolymerised by exposure to UVirradiation.
 35. The process of claim 34, wherein the polymerisablecompounds are photopolymerised by exposure to UV irradiation through aphotomask.
 36. A process of preparing an LC medium comprising of mixinga liquid-crystalline component B) as defined in claim 1, with one ormore polymerisable compounds, or with component A), as defined in claim1, and optionally with further LC compounds and/or additives.